diff --git a/idea/src/org/jetbrains/kotlin/idea/KotlinFoldingBuilder.kt b/idea/src/org/jetbrains/kotlin/idea/KotlinFoldingBuilder.kt
index 12439c6260f..ab6e56c57c9 100644
--- a/idea/src/org/jetbrains/kotlin/idea/KotlinFoldingBuilder.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/KotlinFoldingBuilder.kt
@@ -42,7 +42,7 @@ public class KotlinFoldingBuilder : CustomFoldingBuilder(), DumbAware {
             return
         }
         val imports = root.getImportDirectives()
-        if (imports.size() > 1) {
+        if (imports.size > 1) {
             val importKeyword = imports.get(0).getFirstChild()
             val startOffset = importKeyword.endOffset + 1
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/KotlinQuickDocumentationProvider.kt b/idea/src/org/jetbrains/kotlin/idea/KotlinQuickDocumentationProvider.kt
index 30f4da619ee..5f1079cb50a 100644
--- a/idea/src/org/jetbrains/kotlin/idea/KotlinQuickDocumentationProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/KotlinQuickDocumentationProvider.kt
@@ -80,7 +80,7 @@ public class KotlinQuickDocumentationProvider : AbstractDocumentationProvider()
     }
 
     companion object {
-        private val LOG = Logger.getInstance(javaClass<KotlinQuickDocumentationProvider>())
+        private val LOG = Logger.getInstance(KotlinQuickDocumentationProvider::class.java)
 
         private val DESCRIPTOR_RENDERER = DescriptorRenderer.HTML.withOptions {
             nameShortness = NameShortness.SHORT
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/ConfigureKotlinInProjectAction.kt b/idea/src/org/jetbrains/kotlin/idea/actions/ConfigureKotlinInProjectAction.kt
index 82e0aec901e..41d32d9b206 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/ConfigureKotlinInProjectAction.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/ConfigureKotlinInProjectAction.kt
@@ -42,7 +42,7 @@ public abstract class ConfigureKotlinInProjectAction : AnAction() {
         val configurators = getAbleToRunConfigurators(project)
 
         when {
-            configurators.size() == 1 -> configurators.first().configure(project)
+            configurators.size == 1 -> configurators.first().configure(project)
             configurators.isEmpty() -> Messages.showErrorDialog("There aren't configurators available", e.getPresentation().getText()!!)
             else -> {
                 Messages.showErrorDialog("More than one configurator is available", e.getPresentation().getText()!!)
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/JavaToKotlinAction.kt b/idea/src/org/jetbrains/kotlin/idea/actions/JavaToKotlinAction.kt
index 400858db376..e5aa11c763a 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/JavaToKotlinAction.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/JavaToKotlinAction.kt
@@ -68,7 +68,7 @@ public class JavaToKotlinAction : AnAction() {
                     result.add(virtualFile)
                 }
                 catch (e: IOException) {
-                    MessagesEx.error(psiFile.getProject(), e.getMessage()).showLater()
+                    MessagesEx.error(psiFile.getProject(), e.message).showLater()
                 }
             }
             return result
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/ShowExpressionTypeAction.kt b/idea/src/org/jetbrains/kotlin/idea/actions/ShowExpressionTypeAction.kt
index 43e66aa68af..d7b624ac882 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/ShowExpressionTypeAction.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/ShowExpressionTypeAction.kt
@@ -46,7 +46,7 @@ public class ShowExpressionTypeAction : AnAction() {
         val type = if (editor.getSelectionModel().hasSelection()) {
             val startOffset = editor.getSelectionModel().getSelectionStart()
             val endOffset = editor.getSelectionModel().getSelectionEnd()
-            val expression = CodeInsightUtilCore.findElementInRange<KtExpression>(psiFile, startOffset, endOffset, javaClass<KtExpression>(), KotlinLanguage.INSTANCE) ?: return
+            val expression = CodeInsightUtilCore.findElementInRange<KtExpression>(psiFile, startOffset, endOffset, KtExpression::class.java, KotlinLanguage.INSTANCE) ?: return
             typeByExpression(expression)
         }
         else {
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/generate/KotlinGenerateTestSupportActionBase.kt b/idea/src/org/jetbrains/kotlin/idea/actions/generate/KotlinGenerateTestSupportActionBase.kt
index 77e25b5b119..d6ff5724c18 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/generate/KotlinGenerateTestSupportActionBase.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/generate/KotlinGenerateTestSupportActionBase.kt
@@ -179,7 +179,7 @@ abstract class KotlinGenerateTestSupportActionBase(
                 setupEditorSelection(editor, functionInPlace)
             }
             catch (e: IncorrectOperationException) {
-                HintManager.getInstance().showErrorHint(editor, "Cannot generate method: " + e.getMessage())
+                HintManager.getInstance().showErrorHint(editor, "Cannot generate method: " + e.message)
             }
         }
     }
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/internal/CheckPartialBodyResolveAction.kt b/idea/src/org/jetbrains/kotlin/idea/actions/internal/CheckPartialBodyResolveAction.kt
index cf26d55cb9a..75ac706316a 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/internal/CheckPartialBodyResolveAction.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/internal/CheckPartialBodyResolveAction.kt
@@ -66,7 +66,7 @@ public class CheckPartialBodyResolveAction : AnAction() {
         //TODO: drop resolve caches if any
         val progressIndicator = ProgressManager.getInstance().getProgressIndicator()
         for ((i, file) in files.withIndex()) {
-            progressIndicator?.setText("Checking resolve $i of ${files.size()}...")
+            progressIndicator?.setText("Checking resolve $i of ${files.size}...")
             progressIndicator?.setText2(file.getVirtualFile().getPath())
 
             val partialResolveDump = dumpResolve(file) { element, resolutionFacade ->
@@ -96,11 +96,11 @@ public class CheckPartialBodyResolveAction : AnAction() {
                 return
             }
 
-            progressIndicator?.setFraction((i + 1) / files.size().toDouble())
+            progressIndicator?.setFraction((i + 1) / files.size.toDouble())
         }
 
         SwingUtilities.invokeLater {
-            Messages.showInfoMessage(project, "Analyzed ${files.size()} file(s). No resolve difference found. ", "Success")
+            Messages.showInfoMessage(project, "Analyzed ${files.size} file(s). No resolve difference found. ", "Success")
         }
     }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/actions/internal/FindImplicitNothingAction.kt b/idea/src/org/jetbrains/kotlin/idea/actions/internal/FindImplicitNothingAction.kt
index dd3bb0e3bdf..d279d344680 100644
--- a/idea/src/org/jetbrains/kotlin/idea/actions/internal/FindImplicitNothingAction.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/actions/internal/FindImplicitNothingAction.kt
@@ -62,7 +62,7 @@ public class FindImplicitNothingAction : AnAction() {
         val progressIndicator = ProgressManager.getInstance().getProgressIndicator()
         val found = ArrayList<KtCallExpression>()
         for ((i, file) in files.withIndex()) {
-            progressIndicator?.setText("Scanning files: $i of ${files.size()} file. ${found.size()} occurences found")
+            progressIndicator?.setText("Scanning files: $i of ${files.size} file. ${found.size} occurences found")
             progressIndicator?.setText2(file.getVirtualFile().getPath())
 
             val resolutionFacade = file.getResolutionFacade()
@@ -91,7 +91,7 @@ public class FindImplicitNothingAction : AnAction() {
                 }
             })
 
-            progressIndicator?.setFraction((i + 1) / files.size().toDouble())
+            progressIndicator?.setFraction((i + 1) / files.size.toDouble())
         }
 
         SwingUtilities.invokeLater {
@@ -102,7 +102,7 @@ public class FindImplicitNothingAction : AnAction() {
                 UsageViewManager.getInstance(project).showUsages(arrayOf<UsageTarget>(), usages, presentation)
             }
             else {
-                Messages.showInfoMessage(project, "Not found in ${files.size()} file(s)", "Not Found")
+                Messages.showInfoMessage(project, "Not found in ${files.size} file(s)", "Not Found")
             }
         }
     }
diff --git a/idea/src/org/jetbrains/kotlin/idea/caches/FileAttributeServiceImpl.kt b/idea/src/org/jetbrains/kotlin/idea/caches/FileAttributeServiceImpl.kt
index 40a8572169c..b6c7c726846 100644
--- a/idea/src/org/jetbrains/kotlin/idea/caches/FileAttributeServiceImpl.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/caches/FileAttributeServiceImpl.kt
@@ -35,7 +35,7 @@ public class FileAttributeServiceImpl : FileAttributeService {
 
         attribute.writeAttribute(file).use {
             DataInputOutputUtil.writeTIME(it, data.timeStamp)
-            DataInputOutputUtil.writeINT(it, data.value?.ordinal() ?: -1)
+            DataInputOutputUtil.writeINT(it, data.value?.ordinal ?: -1)
         }
 
         return data
diff --git a/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinCopyPasteReferenceProcessor.kt b/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinCopyPasteReferenceProcessor.kt
index 819717f67b1..f278ecf8e91 100644
--- a/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinCopyPasteReferenceProcessor.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinCopyPasteReferenceProcessor.kt
@@ -65,7 +65,7 @@ import java.util.*
 
 //NOTE: this class is based on CopyPasteReferenceProcessor and JavaCopyPasteReferenceProcessor
 public class KotlinCopyPasteReferenceProcessor() : CopyPastePostProcessor<KotlinReferenceTransferableData>() {
-    private val LOG = Logger.getInstance(javaClass<KotlinCopyPasteReferenceProcessor>())
+    private val LOG = Logger.getInstance(KotlinCopyPasteReferenceProcessor::class.java)
 
     private val IGNORE_REFERENCES_INSIDE: Array<Class<out KtElement>> = arrayOf(
             KtImportList::class.java,
@@ -144,7 +144,7 @@ public class KotlinCopyPasteReferenceProcessor() : CopyPastePostProcessor<Kotlin
 
             val descriptors = reference.resolveToDescriptors(element.analyze()) //TODO: we could use partial body resolve for all references together
             //check whether this reference is unambiguous
-            if (reference !is KtMultiReference<*> && descriptors.size() > 1) return@forEachDescendantOfType
+            if (reference !is KtMultiReference<*> && descriptors.size > 1) return@forEachDescendantOfType
 
             for (descriptor in descriptors) {
                 val declarations = DescriptorToSourceUtilsIde.getAllDeclarations(file.getProject(), descriptor)
@@ -302,7 +302,7 @@ public class KotlinCopyPasteReferenceProcessor() : CopyPastePostProcessor<Kotlin
     private fun findImportableDescriptors(fqName: FqName, file: KtFile): Collection<DeclarationDescriptor> {
         return file.resolveImportReference(fqName).filterNot {
             /*TODO: temporary hack until we don't have ability to insert qualified reference into root package*/
-            DescriptorUtils.getParentOfType(it, javaClass<PackageFragmentDescriptor>())?.fqName?.isRoot() ?: false
+            DescriptorUtils.getParentOfType(it, PackageFragmentDescriptor::class.java)?.fqName?.isRoot() ?: false
         }
     }
 
@@ -329,7 +329,7 @@ public class KotlinCopyPasteReferenceProcessor() : CopyPastePostProcessor<Kotlin
     }
 
     private fun toTextRanges(startOffsets: IntArray, endOffsets: IntArray): List<TextRange> {
-        assert(startOffsets.size() == endOffsets.size())
+        assert(startOffsets.size == endOffsets.size)
         return startOffsets.indices.map { TextRange(startOffsets[it], endOffsets[it]) }
     }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinReferenceTransferableData.kt b/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinReferenceTransferableData.kt
index 7fc093ebc78..bc54c62cbad 100644
--- a/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinReferenceTransferableData.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/codeInsight/KotlinReferenceTransferableData.kt
@@ -29,7 +29,7 @@ public class KotlinReferenceTransferableData(
 
     override fun getFlavor() = KotlinReferenceData.dataFlavor
 
-    override fun getOffsetCount() = data.size() * 2
+    override fun getOffsetCount() = data.size * 2
 
     override fun getOffsets(offsets: IntArray, index: Int): Int {
         var i = index
@@ -49,7 +49,7 @@ public class KotlinReferenceTransferableData(
         return i
     }
 
-    public override fun clone() = KotlinReferenceTransferableData(Array(data.size(), {  data[it].clone() }))
+    public override fun clone() = KotlinReferenceTransferableData(Array(data.size, {  data[it].clone() }))
 }
 
 public class KotlinReferenceData(
@@ -100,7 +100,7 @@ public class KotlinReferenceData(
     companion object {
         public val dataFlavor: DataFlavor? by lazy {
             try {
-                val dataClass = javaClass<KotlinReferenceData>()
+                val dataClass = KotlinReferenceData::class.java
                 DataFlavor(DataFlavor.javaJVMLocalObjectMimeType + ";class=" + dataClass.getName(),
                            "KotlinReferenceData",
                            dataClass.getClassLoader())
diff --git a/idea/src/org/jetbrains/kotlin/idea/conversion/copy/ConvertJavaCopyPastePostProcessor.kt b/idea/src/org/jetbrains/kotlin/idea/conversion/copy/ConvertJavaCopyPastePostProcessor.kt
index ba384eba174..8832283379b 100644
--- a/idea/src/org/jetbrains/kotlin/idea/conversion/copy/ConvertJavaCopyPastePostProcessor.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/conversion/copy/ConvertJavaCopyPastePostProcessor.kt
@@ -145,7 +145,7 @@ public class ConvertJavaCopyPastePostProcessor : CopyPastePostProcessor<TextBloc
                 val startOffset = bounds.getStartOffset()
                 document.replaceString(startOffset, bounds.getEndOffset(), text)
 
-                val endOffsetAfterCopy = startOffset + text.length()
+                val endOffsetAfterCopy = startOffset + text.length
                 editor.getCaretModel().moveToOffset(endOffsetAfterCopy)
 
                 var newBounds = insertImports(TextRange(startOffset, endOffsetAfterCopy), referenceData, explicitImports)
@@ -211,7 +211,7 @@ public class ConvertJavaCopyPastePostProcessor : CopyPastePostProcessor<TextBloc
     private fun buildReferenceData(text: String, parseContext: ParseContext, importsAndPackage: String, targetFile: KtFile): Collection<KotlinReferenceData> {
         var blockStart: Int? = null
         var blockEnd: Int? = null
-        val fileText = StringBuilder {
+        val fileText = buildString {
             append(importsAndPackage)
 
             val (contextPrefix, contextSuffix) = when (parseContext) {
@@ -221,12 +221,12 @@ public class ConvertJavaCopyPastePostProcessor : CopyPastePostProcessor<TextBloc
 
             append(contextPrefix)
 
-            blockStart = length()
+            blockStart = length
             append(text)
-            blockEnd = length()
+            blockEnd = length
 
             append(contextSuffix)
-        }.toString()
+        }
 
         val dummyFile = KtPsiFactory(targetFile.getProject()).createAnalyzableFile("dummy.kt", fileText, targetFile)
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/conversion/copy/CopiedJavaCode.kt b/idea/src/org/jetbrains/kotlin/idea/conversion/copy/CopiedJavaCode.kt
index 7263e23dd04..27a6c87eb40 100644
--- a/idea/src/org/jetbrains/kotlin/idea/conversion/copy/CopiedJavaCode.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/conversion/copy/CopiedJavaCode.kt
@@ -29,6 +29,6 @@ class CopiedJavaCode(val fileText: String, val startOffsets: IntArray, val endOf
     public override fun setOffsets(offsets: IntArray?, index: Int) = index
 
     companion object {
-        val DATA_FLAVOR: DataFlavor = DataFlavor(javaClass<ConvertJavaCopyPastePostProcessor>(), "class: ConvertJavaCopyPastePostProcessor")
+        val DATA_FLAVOR: DataFlavor = DataFlavor(ConvertJavaCopyPastePostProcessor::class.java, "class: ConvertJavaCopyPastePostProcessor")
     }
 }
diff --git a/idea/src/org/jetbrains/kotlin/idea/conversion/copy/DataForConversion.kt b/idea/src/org/jetbrains/kotlin/idea/conversion/copy/DataForConversion.kt
index 9a334f8a49a..f970ca72998 100644
--- a/idea/src/org/jetbrains/kotlin/idea/conversion/copy/DataForConversion.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/conversion/copy/DataForConversion.kt
@@ -33,7 +33,7 @@ data class DataForConversion private constructor(
         fun prepare(copiedCode: CopiedJavaCode, project: Project): DataForConversion  {
             val startOffsets = copiedCode.startOffsets.clone()
             val endOffsets = copiedCode.endOffsets.clone()
-            assert(startOffsets.size() == endOffsets.size()) { "Must have the same size" }
+            assert(startOffsets.size == endOffsets.size) { "Must have the same size" }
 
             var fileText = copiedCode.fileText
             var file = PsiFileFactory.getInstance(project).createFileFromText(JavaLanguage.INSTANCE, fileText) as PsiJavaFile
@@ -98,15 +98,15 @@ data class DataForConversion private constructor(
 
             if (rangesToDrop.isEmpty()) return null
 
-            val newFileText = StringBuilder {
+            val newFileText = buildString {
                 var offset = 0
                 for (range in rangesToDrop) {
                     assert(range.start >= offset)
                     append(fileText.substring(offset, range.start))
                     offset = range.end
                 }
-                append(fileText.substring(offset, fileText.length()))
-            }.toString()
+                append(fileText.substring(offset, fileText.length))
+            }
 
             fun IntArray.update() {
                 for (range in rangesToDrop.asReversed()) {
@@ -226,7 +226,7 @@ data class DataForConversion private constructor(
         private fun shouldExpandToChildren(element: PsiElement) = element is PsiModifierList
 
         private fun buildImportsAndPackage(sourceFile: PsiJavaFile): String {
-            return StringBuilder {
+            return buildString {
                 val packageName = sourceFile.getPackageName()
                 if (!packageName.isEmpty()) {
                     append("package $packageName\n")
@@ -248,7 +248,7 @@ data class DataForConversion private constructor(
                     }
                     //TODO: static imports
                 }
-            }.toString()
+            }
         }
     }
 }
diff --git a/idea/src/org/jetbrains/kotlin/idea/coverage/KotlinCoverageExtension.kt b/idea/src/org/jetbrains/kotlin/idea/coverage/KotlinCoverageExtension.kt
index d030f670a51..13161f651de 100644
--- a/idea/src/org/jetbrains/kotlin/idea/coverage/KotlinCoverageExtension.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/coverage/KotlinCoverageExtension.kt
@@ -40,7 +40,7 @@ import org.jetbrains.kotlin.psi.KtFile
 import java.io.File
 
 public class KotlinCoverageExtension(): JavaCoverageEngineExtension() {
-    private val LOG = Logger.getInstance(javaClass<KotlinCoverageExtension>())
+    private val LOG = Logger.getInstance(KotlinCoverageExtension::class.java)
 
     override fun isApplicableTo(conf: RunConfigurationBase?): Boolean = conf is JetRunConfiguration
 
@@ -96,7 +96,7 @@ public class KotlinCoverageExtension(): JavaCoverageEngineExtension() {
     }
 
     companion object {
-        private val LOG = Logger.getInstance(javaClass<KotlinCoverageExtension>())
+        private val LOG = Logger.getInstance(KotlinCoverageExtension::class.java)
 
         fun collectGeneratedClassQualifiedNames(outputRoot: VirtualFile?, file: KtFile): List<String>? {
             val existingClassFiles = getClassesGeneratedFromFile(outputRoot, file)
diff --git a/idea/src/org/jetbrains/kotlin/idea/editor/KotlinEnterHandler.kt b/idea/src/org/jetbrains/kotlin/idea/editor/KotlinEnterHandler.kt
index 5a0caaa4f09..7aa983894e0 100644
--- a/idea/src/org/jetbrains/kotlin/idea/editor/KotlinEnterHandler.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/editor/KotlinEnterHandler.kt
@@ -37,7 +37,7 @@ import org.jetbrains.kotlin.psi.psiUtil.*
 
 public class KotlinEnterHandler: EnterHandlerDelegateAdapter() {
     companion object {
-        private val LOG = Logger.getInstance(javaClass<KotlinEnterHandler>())
+        private val LOG = Logger.getInstance(KotlinEnterHandler::class.java)
         private val FORCE_INDENT_IN_LAMBDA_AFTER = TokenSet.create(KtTokens.ARROW, KtTokens.LBRACE)
     }
 
@@ -61,7 +61,7 @@ public class KotlinEnterHandler: EnterHandlerDelegateAdapter() {
         val text = document.getCharsSequence()
         val caretOffset = caretOffsetRef.get()!!.toInt()
 
-        if (caretOffset !in 0..text.length()) return EnterHandlerDelegate.Result.Continue
+        if (caretOffset !in 0..text.length) return EnterHandlerDelegate.Result.Continue
 
         val elementAt = file.findElementAt(caretOffset)
         if (elementAt is PsiWhiteSpace && ("\n" in elementAt.getText()!!)) return EnterHandlerDelegate.Result.Continue
diff --git a/idea/src/org/jetbrains/kotlin/idea/editor/KotlinSmartEnterHandler.kt b/idea/src/org/jetbrains/kotlin/idea/editor/KotlinSmartEnterHandler.kt
index b2b40d2eedf..411263b0843 100644
--- a/idea/src/org/jetbrains/kotlin/idea/editor/KotlinSmartEnterHandler.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/editor/KotlinSmartEnterHandler.kt
@@ -92,8 +92,8 @@ public class KotlinSmartEnterHandler: SmartEnterProcessorWithFixers() {
 
         caretOffset = CharArrayUtil.shiftBackward(chars, caretOffset - 1, " \t") + 1
 
-        if (CharArrayUtil.regionMatches(chars, caretOffset - "{}".length(), "{}") ||
-                CharArrayUtil.regionMatches(chars, caretOffset - "{\n}".length(), "{\n}")) {
+        if (CharArrayUtil.regionMatches(chars, caretOffset - "{}".length, "{}") ||
+            CharArrayUtil.regionMatches(chars, caretOffset - "{\n}".length, "{\n}")) {
             commit(editor)
             val settings = CodeStyleSettingsManager.getSettings(file.getProject())
             val old = settings.KEEP_SIMPLE_BLOCKS_IN_ONE_LINE
diff --git a/idea/src/org/jetbrains/kotlin/idea/editor/fixers/KotlinDoWhileFixer.kt b/idea/src/org/jetbrains/kotlin/idea/editor/fixers/KotlinDoWhileFixer.kt
index 20ebeea0302..c6201ca1c3e 100644
--- a/idea/src/org/jetbrains/kotlin/idea/editor/fixers/KotlinDoWhileFixer.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/editor/fixers/KotlinDoWhileFixer.kt
@@ -34,16 +34,16 @@ public class KotlinDoWhileFixer : SmartEnterProcessorWithFixers.Fixer<KotlinSmar
         val whileKeyword = psiElement.getWhileKeyword()
         if (body == null) {
             if (whileKeyword == null) {
-                doc.replaceString(start, start + "do".length(), "do {} while()")
+                doc.replaceString(start, start + "do".length, "do {} while()")
             }
             else {
-                doc.insertString(start + "do".length(), "{}")
+                doc.insertString(start + "do".length, "{}")
             }
             return
         }
         else if (whileKeyword != null && body !is KtBlockExpression && body.startLine(doc) > psiElement.startLine(doc)) {
             doc.insertString(whileKeyword.range.start, "}")
-            doc.insertString(start + "do".length(), "{")
+            doc.insertString(start + "do".length, "{")
 
             return
         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/editor/fixers/MissingConditionFixer.kt b/idea/src/org/jetbrains/kotlin/idea/editor/fixers/MissingConditionFixer.kt
index f6e3dc2654e..2944a7d6ab0 100644
--- a/idea/src/org/jetbrains/kotlin/idea/editor/fixers/MissingConditionFixer.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/editor/fixers/MissingConditionFixer.kt
@@ -42,7 +42,7 @@ abstract class MissingConditionFixer<T: PsiElement>() : SmartEnterProcessorWithF
                 stopOffset = Math.min(stopOffset, workElement.range.end)
 
                 doc.replaceString(workElement.range.start, stopOffset, "$keyword ()")
-                processor.registerUnresolvedError(workElement.range.start + "$keyword (".length())
+                processor.registerUnresolvedError(workElement.range.start + "$keyword (".length)
             }
             else {
                 processor.registerUnresolvedError(lParen.range.end)
diff --git a/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinDeclarationGroupRuleProvider.kt b/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinDeclarationGroupRuleProvider.kt
index ea53754ae7f..265345ff48b 100644
--- a/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinDeclarationGroupRuleProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinDeclarationGroupRuleProvider.kt
@@ -36,7 +36,7 @@ public class KotlinDeclarationGroupRuleProvider : FileStructureGroupRuleProvider
             val containingFile = element.getContainingFile()
             if (containingFile !is KtFile) return null
 
-            return PsiTreeUtil.getTopmostParentOfType(element, javaClass<KtNamedDeclaration>())?.let { container ->
+            return PsiTreeUtil.getTopmostParentOfType(element, KtNamedDeclaration::class.java)?.let { container ->
                 PsiNamedElementUsageGroupBase(container)
             }
         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinFindUsagesHandlerFactory.kt b/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinFindUsagesHandlerFactory.kt
index 0bce891ec88..c3b54d16629 100644
--- a/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinFindUsagesHandlerFactory.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/findUsages/KotlinFindUsagesHandlerFactory.kt
@@ -120,7 +120,7 @@ public class KotlinFindUsagesHandlerFactory(project: Project) : FindUsagesHandle
     }
 
     private fun handlerForMultiple(originalDeclaration: KtNamedDeclaration, declarations: Collection<PsiElement>): FindUsagesHandler {
-        return when (declarations.size()) {
+        return when (declarations.size) {
             0 -> FindUsagesHandler.NULL_HANDLER
 
             1 -> {
diff --git a/idea/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt b/idea/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt
index 5040f36d342..7151f50e0b4 100644
--- a/idea/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/formatter/kotlinSpacingRules.kt
@@ -44,7 +44,7 @@ fun SpacingBuilder.afterInside(element: IElementType, tokenSet: TokenSet, spacin
 }
 
 fun createSpacingBuilder(settings: CodeStyleSettings): KotlinSpacingBuilder {
-    val jetSettings = settings.getCustomSettings(javaClass<KotlinCodeStyleSettings>())!!
+    val jetSettings = settings.getCustomSettings(KotlinCodeStyleSettings::class.java)!!
     val jetCommonSettings = settings.getCommonSettings(KotlinLanguage.INSTANCE)!!
 
     return rules(settings) {
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinColorSettingsPage.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinColorSettingsPage.kt
index d54b9521843..37bd0fee85b 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinColorSettingsPage.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinColorSettingsPage.kt
@@ -93,7 +93,7 @@ var <PROPERTY_WITH_BACKING_FIELD><PACKAGE_PROPERTY><MUTABLE_VARIABLE>globalCount
 
     override fun getAdditionalHighlightingTagToDescriptorMap(): Map<String, TextAttributesKey> {
         val map = HashMap<String, TextAttributesKey>()
-        for (field in javaClass<KotlinHighlightingColors>().getFields()) {
+        for (field in KotlinHighlightingColors::class.java.getFields()) {
             if (Modifier.isStatic(field.getModifiers())) {
                 try {
                     map.put(field.getName(), field.get(null) as TextAttributesKey)
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinHighlightExitPointsHandlerFactory.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinHighlightExitPointsHandlerFactory.kt
index dd6c5f0ae65..5a6332918d9 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinHighlightExitPointsHandlerFactory.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinHighlightExitPointsHandlerFactory.kt
@@ -44,8 +44,8 @@ public class KotlinHighlightExitPointsHandlerFactory: HighlightUsagesHandlerFact
         if (target is LeafPsiElement && (target.getElementType() in RETURN_AND_THROW)) {
             val returnOrThrow = PsiTreeUtil.getParentOfType<KtExpression>(
                     target,
-                    javaClass<KtReturnExpression>(),
-                    javaClass<KtThrowExpression>()
+                    KtReturnExpression::class.java,
+                    KtThrowExpression::class.java
             ) ?: return null
 
             return MyHandler(editor, file, returnOrThrow)
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt
index f2ffaa7d56c..0e865382cf2 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/KotlinLineMarkerProvider.kt
@@ -168,7 +168,7 @@ private fun collectOverriddenPropertyAccessors(properties: Collection<KtProperty
         }
     }
 
-    val classes = collectContainingClasses(mappingToJava.keySet())
+    val classes = collectContainingClasses(mappingToJava.keys)
 
     for (property in getOverriddenDeclarations(mappingToJava, classes)) {
         ProgressManager.checkCanceled()
@@ -198,7 +198,7 @@ private fun collectOverriddenFunctions(functions: Collection<KtNamedFunction>, r
         }
     }
 
-    val classes = collectContainingClasses(mappingToJava.keySet())
+    val classes = collectContainingClasses(mappingToJava.keys)
 
     for (function in getOverriddenDeclarations(mappingToJava, classes)) {
         ProgressManager.checkCanceled()
diff --git a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenFunctionMarker.kt b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenFunctionMarker.kt
index 06c931aa206..1224539ff4d 100644
--- a/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenFunctionMarker.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/highlighter/markers/OverridenFunctionMarker.kt
@@ -120,7 +120,7 @@ public fun navigateToOverriddenMethod(e: MouseEvent?, method: PsiMethod) {
     PsiElementListNavigator.openTargets(
             e,
             overridingJavaMethods.toTypedArray(),
-            methodsUpdater.getCaption(overridingJavaMethods.size()),
+            methodsUpdater.getCaption(overridingJavaMethods.size),
             "Overriding declarations of " + method.getName(),
             renderer,
             methodsUpdater)
diff --git a/idea/src/org/jetbrains/kotlin/idea/imports/KotlinImportOptimizer.kt b/idea/src/org/jetbrains/kotlin/idea/imports/KotlinImportOptimizer.kt
index f75a3e6bbff..6ea20ee12e5 100644
--- a/idea/src/org/jetbrains/kotlin/idea/imports/KotlinImportOptimizer.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/imports/KotlinImportOptimizer.kt
@@ -239,13 +239,13 @@ public class KotlinImportOptimizer() : ImportOptimizer {
             }
 
             //TODO: drop unused aliases?
-            aliasImports.mapTo(importsToGenerate) { ImportPath(it.getValue(), false, it.getKey())}
+            aliasImports.mapTo(importsToGenerate) { ImportPath(it.value, false, it.key)}
 
             val sortedImportsToGenerate = importsToGenerate.sortedWith(importInsertHelper.importSortComparator)
 
             // check if no changes to imports required
             val oldImports = file.importDirectives
-            if (oldImports.size() == sortedImportsToGenerate.size() && oldImports.map { it.importPath } == sortedImportsToGenerate) return null
+            if (oldImports.size == sortedImportsToGenerate.size && oldImports.map { it.importPath } == sortedImportsToGenerate) return null
 
             return sortedImportsToGenerate
         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/ConflictingExtensionPropertyInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/ConflictingExtensionPropertyInspection.kt
index 8b450d4e6d6..770d7e7d615 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/ConflictingExtensionPropertyInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/ConflictingExtensionPropertyInspection.kt
@@ -197,7 +197,7 @@ public class ConflictingExtensionPropertyInspection : AbstractKotlinInspection()
                                     ReferencesSearch.search(declaration, searchScope)
                                             .filterIsInstance<KtSimpleNameReference>()
                                             .mapNotNull { ref -> ref.expression.getStrictParentOfType<KtImportDirective>() }
-                                            .filter { import -> !import.isAllUnder && import.targetDescriptors().size() == 1 }
+                                            .filter { import -> !import.isAllUnder && import.targetDescriptors().size == 1 }
                                 }
                                 UIUtil.invokeLaterIfNeeded {
                                     project.executeWriteCommand(text) {
diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinInvalidBundleOrPropertyInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinInvalidBundleOrPropertyInspection.kt
index 3e24928ee6f..7fbe90402eb 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinInvalidBundleOrPropertyInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinInvalidBundleOrPropertyInspection.kt
@@ -75,13 +75,13 @@ class KotlinInvalidBundleOrPropertyInspection : AbstractKotlinInspection() {
                 if (keyArgumentIndex < 0) return
 
                 val callable = resolvedCall.resultingDescriptor
-                if (callable.valueParameters.size() != keyArgumentIndex + 2) return
+                if (callable.valueParameters.size != keyArgumentIndex + 2) return
 
                 val messageArgument = resolvedArguments[keyArgumentIndex + 1] as? VarargValueArgument ?: return
                 if (messageArgument.arguments.singleOrNull()?.getSpreadElement() != null) return
 
                 val expectedArgumentCount = JavaI18nUtil.getPropertyValuePlaceholdersCount(property.value ?: "")
-                val actualArgumentCount = messageArgument.arguments.size()
+                val actualArgumentCount = messageArgument.arguments.size
                 if (actualArgumentCount < expectedArgumentCount) {
                     val description = CodeInsightBundle.message(
                             "property.has.more.parameters.than.passed",
diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt
index 117793f6c24..bdace19b1d5 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/KotlinUnusedImportInspection.kt
@@ -85,7 +85,7 @@ class KotlinUnusedImportInspection : AbstractKotlinInspection() {
 
         val problems = ArrayList<ProblemDescriptor>()
 
-        val importPaths = HashSet<ImportPath>(directives.size())
+        val importPaths = HashSet<ImportPath>(directives.size)
 
         for (directive in directives) {
             val importPath = directive.importPath ?: continue
diff --git a/idea/src/org/jetbrains/kotlin/idea/j2k/IdeaDocCommentConverter.kt b/idea/src/org/jetbrains/kotlin/idea/j2k/IdeaDocCommentConverter.kt
index f2a2e5e3b32..74260eaa901 100644
--- a/idea/src/org/jetbrains/kotlin/idea/j2k/IdeaDocCommentConverter.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/j2k/IdeaDocCommentConverter.kt
@@ -35,7 +35,7 @@ import org.jetbrains.kotlin.j2k.content
 
 object IdeaDocCommentConverter : DocCommentConverter {
     override fun convertDocComment(docComment: PsiDocComment): String {
-        val html = StringBuilder {
+        val html = buildString {
             appendJavadocElements(docComment.getDescriptionElements())
 
             tagsLoop@
@@ -46,7 +46,7 @@ object IdeaDocCommentConverter : DocCommentConverter {
                     else -> appendJavadocElements(tag.getChildren()).append("\n")
                 }
             }
-        }.toString()
+        }
 
         if (html.trim().isEmpty() && docComment.findTagByName("deprecated") != null) {
             // @deprecated was the only content of the doc comment; we can drop the comment
diff --git a/idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessings.kt b/idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessings.kt
index 451ca1b13bb..26ade1883c9 100644
--- a/idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessings.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessings.kt
@@ -118,7 +118,7 @@ object J2KPostProcessingRegistrar {
     ) {
         _processings.add(object : J2kPostProcessing {
             override fun createAction(element: KtElement, diagnostics: Diagnostics): (() -> Unit)? {
-                if (!javaClass<TElement>().isInstance(element)) return null
+                if (!TElement::class.java.isInstance(element)) return null
                 val tElement = element as TElement
                 if (intention.applicabilityRange(tElement) == null) return null
                 if (!additionalChecker(tElement)) return null
@@ -140,7 +140,7 @@ object J2KPostProcessingRegistrar {
     ) {
         _processings.add(object : J2kPostProcessing {
             override fun createAction(element: KtElement, diagnostics: Diagnostics): (() -> Unit)? {
-                if (!javaClass<TElement>().isInstance(element)) return null
+                if (!TElement::class.java.isInstance(element)) return null
                 val diagnostic = diagnostics.forElement(element).firstOrNull { it.factory == diagnosticFactory } ?: return null
                 return fixFactory(element as TElement, diagnostic)
             }
diff --git a/idea/src/org/jetbrains/kotlin/idea/kdoc/KDocRenderer.kt b/idea/src/org/jetbrains/kotlin/idea/kdoc/KDocRenderer.kt
index 85dcce43ea7..649d2fca04b 100644
--- a/idea/src/org/jetbrains/kotlin/idea/kdoc/KDocRenderer.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/kdoc/KDocRenderer.kt
@@ -64,7 +64,7 @@ object KDocRenderer {
             else {
                 to.append(tag.getContent())
             }
-            if (index < seeTags.size() - 1) {
+            if (index < seeTags.size - 1) {
                 to.append(", ")
             }
         }
@@ -211,8 +211,8 @@ object KDocRenderer {
     }
 
     fun StringBuilder.trimEnd() {
-        while (length() > 0 && this[length() - 1] == ' ') {
-            deleteCharAt(length() - 1)
+        while (length > 0 && this[length - 1] == ' ') {
+            deleteCharAt(length - 1)
         }
     }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/parameterInfo/KotlinFunctionParameterInfoHandler.kt b/idea/src/org/jetbrains/kotlin/idea/parameterInfo/KotlinFunctionParameterInfoHandler.kt
index c4478cfcf09..9886e8a73ae 100644
--- a/idea/src/org/jetbrains/kotlin/idea/parameterInfo/KotlinFunctionParameterInfoHandler.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/parameterInfo/KotlinFunctionParameterInfoHandler.kt
@@ -160,7 +160,7 @@ abstract class KotlinParameterInfoWithCallHandlerBase<TArgumentList : KtElement,
 
         var boldStartOffset = -1
         var boldEndOffset = -1
-        val text = StringBuilder {
+        val text = buildString {
             val usedParameterIndices = HashSet<Int>()
             var namedMode = false
 
@@ -172,19 +172,19 @@ abstract class KotlinParameterInfoWithCallHandlerBase<TArgumentList : KtElement,
             val includeParameterNames = !substitutedDescriptor.hasSynthesizedParameterNames()
 
             fun appendParameter(parameter: ValueParameterDescriptor) {
-                if (length() > 0) {
+                if (length > 0) {
                     append(", ")
                 }
 
                 val highlightParameter = parameter.index == highlightParameterIndex
                 if (highlightParameter) {
-                    boldStartOffset = length()
+                    boldStartOffset = length
                 }
 
                 append(renderParameter(parameter, includeParameterNames, namedMode, project))
 
                 if (highlightParameter) {
-                    boldEndOffset = length()
+                    boldEndOffset = length
                 }
             }
 
@@ -206,10 +206,10 @@ abstract class KotlinParameterInfoWithCallHandlerBase<TArgumentList : KtElement,
                 }
             }
 
-            if (length() == 0) {
+            if (length == 0) {
                 append(CodeInsightBundle.message("parameter.info.no.parameters"))
             }
-        }.toString()
+        }
 
 
         val color = if (isResolvedToDescriptor(call, itemToShow, bindingContext))
@@ -234,7 +234,7 @@ abstract class KotlinParameterInfoWithCallHandlerBase<TArgumentList : KtElement,
     override fun getParametersForDocumentation(item: FunctionDescriptor, context: ParameterInfoContext) = emptyArray<Any>()
 
     private fun renderParameter(parameter: ValueParameterDescriptor, includeName: Boolean, named: Boolean, project: Project): String {
-        return StringBuilder {
+        return buildString {
             if (named) append("[")
 
             if (parameter.varargElementType != null) {
@@ -254,14 +254,14 @@ abstract class KotlinParameterInfoWithCallHandlerBase<TArgumentList : KtElement,
             }
 
             if (named) append("]")
-        }.toString()
+        }
     }
 
     private fun ValueParameterDescriptor.renderDefaultValue(project: Project): String {
         val expression = OptionalParametersHelper.defaultParameterValueExpression(this, project)
         if (expression != null) {
             val text = expression.text
-            if (text.length() <= 32) {
+            if (text.length <= 32) {
                 return text
             }
 
@@ -313,13 +313,13 @@ abstract class KotlinParameterInfoWithCallHandlerBase<TArgumentList : KtElement,
             return SignatureInfo(overload, { null }, null, isGrey = false)
         }
 
-        assert(call.valueArguments.size() >= currentArgumentIndex)
+        assert(call.valueArguments.size >= currentArgumentIndex)
 
         val argumentsBeforeCurrent = call.valueArguments.subList(0, currentArgumentIndex)
 
         val callToUse: Call
         val currentArgument: ValueArgument
-        if (call.valueArguments.size() > currentArgumentIndex) {
+        if (call.valueArguments.size > currentArgumentIndex) {
             currentArgument = call.valueArguments[currentArgumentIndex]
             callToUse = call
         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/properties/referenceProviders.kt b/idea/src/org/jetbrains/kotlin/idea/properties/referenceProviders.kt
index 09bbd6c1e03..c654048a06a 100644
--- a/idea/src/org/jetbrains/kotlin/idea/properties/referenceProviders.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/properties/referenceProviders.kt
@@ -53,7 +53,7 @@ private val PROPERTY_KEY = FqName(AnnotationUtil.PROPERTY_KEY)
 private val PROPERTY_KEY_RESOURCE_BUNDLE = Name.identifier(AnnotationUtil.PROPERTY_KEY_RESOURCE_BUNDLE_PARAMETER)
 
 private fun AnnotationDescriptor.getBundleName(): String? {
-    return allValueArguments.entrySet().singleOrNull { it.key.name == PROPERTY_KEY_RESOURCE_BUNDLE }?.value?.value as? String
+    return allValueArguments.entries.singleOrNull { it.key.name == PROPERTY_KEY_RESOURCE_BUNDLE }?.value?.value as? String
 }
 
 private fun DeclarationDescriptor.getBundleNameByAnnotation(): String? {
@@ -83,7 +83,7 @@ private fun KtExpression.getBundleNameByContext(): String? {
                 ?.getBundleName()
     }
 
-    return resolvedCall.valueArguments.entrySet()
+    return resolvedCall.valueArguments.entries
             .singleOrNull { it.value.arguments.any { it.getArgumentExpression() == expression } }
             ?.key
             ?.getBundleNameByAnnotation()
diff --git a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/KotlinChangeInfo.kt b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/KotlinChangeInfo.kt
index c44e1336e38..762eac786e7 100644
--- a/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/KotlinChangeInfo.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/refactoring/changeSignature/KotlinChangeInfo.kt
@@ -361,7 +361,7 @@ public open class KotlinChangeInfo(
             currentPsiMethods.singleOrNull()?.let { method -> return originalPsiMethods.keysToMap { method } }
 
             val currentSignatures = initCurrentSignatures(currentPsiMethods)
-            return originalSignatures.toMap({ it.method }) { originalSignature ->
+            return originalSignatures.toMapBy({ it.method }) { originalSignature ->
                 var constrainedCurrentSignatures = currentSignatures.map { it.constrainBy(originalSignature) }
                 val maxMandatoryCount = constrainedCurrentSignatures.maxBy { it.mandatoryParams.size }!!.mandatoryParams.size
                 constrainedCurrentSignatures = constrainedCurrentSignatures.filter { it.mandatoryParams.size == maxMandatoryCount }
diff --git a/idea/src/org/jetbrains/kotlin/idea/run/KotlinJUnitRunConfigurationProducer.kt b/idea/src/org/jetbrains/kotlin/idea/run/KotlinJUnitRunConfigurationProducer.kt
index f64087ac77a..86a9724f0e3 100644
--- a/idea/src/org/jetbrains/kotlin/idea/run/KotlinJUnitRunConfigurationProducer.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/run/KotlinJUnitRunConfigurationProducer.kt
@@ -40,7 +40,7 @@ import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 public class KotlinJUnitRunConfigurationProducer : RunConfigurationProducer<JUnitConfiguration>(JUnitConfigurationType.getInstance()) {
     override fun isConfigurationFromContext(configuration: JUnitConfiguration,
                                             context: ConfigurationContext): Boolean {
-        if (RunConfigurationProducer.getInstance(javaClass<PatternConfigurationProducer>()).isMultipleElementsSelected(context)) {
+        if (RunConfigurationProducer.getInstance(PatternConfigurationProducer::class.java).isMultipleElementsSelected(context)) {
             return false
         }
 
@@ -134,7 +134,7 @@ public class KotlinJUnitRunConfigurationProducer : RunConfigurationProducer<JUni
 
     private fun getTestMethodLocation(leaf: PsiElement): Location<PsiMethod>? {
         val function = leaf.getParentOfType<KtNamedFunction>(false) ?: return null
-        val owner = PsiTreeUtil.getParentOfType(function, javaClass<KtFunction>(), javaClass<KtClass>())
+        val owner = PsiTreeUtil.getParentOfType(function, KtFunction::class.java, KtClass::class.java)
 
         if (owner is KtClass) {
             val delegate = LightClassUtil.getPsiClass(owner) ?: return null
diff --git a/idea/src/org/jetbrains/kotlin/idea/run/KotlinRunConfigurationProducer.kt b/idea/src/org/jetbrains/kotlin/idea/run/KotlinRunConfigurationProducer.kt
index 7f8a2bd45ee..6860b47c836 100644
--- a/idea/src/org/jetbrains/kotlin/idea/run/KotlinRunConfigurationProducer.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/run/KotlinRunConfigurationProducer.kt
@@ -113,9 +113,9 @@ public class KotlinRunConfigurationProducer : RunConfigurationProducer<JetRunCon
 
         private fun PsiElement.declarationContainer(strict: Boolean): KtDeclarationContainer? {
             val element = if (strict)
-                PsiTreeUtil.getParentOfType(this, javaClass<KtClassOrObject>(), javaClass<KtFile>())
+                PsiTreeUtil.getParentOfType(this, KtClassOrObject::class.java, KtFile::class.java)
             else
-                PsiTreeUtil.getNonStrictParentOfType(this, javaClass<KtClassOrObject>(), javaClass<KtFile>())
+                PsiTreeUtil.getNonStrictParentOfType(this, KtClassOrObject::class.java, KtFile::class.java)
             return element as KtDeclarationContainer?
         }
 
diff --git a/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiRange.kt b/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiRange.kt
index 331366d5131..df70865e10f 100644
--- a/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiRange.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiRange.kt
@@ -68,7 +68,7 @@ public interface KotlinPsiRange {
                         val range = element
                                 .siblings()
                                 .filter(SIGNIFICANT_FILTER)
-                                .take(elements.size())
+                                .take(elements.size)
                                 .toList()
                                 .toRange()
 
@@ -78,9 +78,9 @@ public interface KotlinPsiRange {
                             matches.add(result)
                         }
                         else {
-                            val matchCountSoFar = matches.size()
+                            val matchCountSoFar = matches.size
                             super.visitKtElement(element)
-                            if (result is UnificationResult.WeaklyMatched && matches.size() == matchCountSoFar) {
+                            if (result is UnificationResult.WeaklyMatched && matches.size == matchCountSoFar) {
                                 matches.add(result)
                             }
                         }
diff --git a/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiUnifier.kt b/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiUnifier.kt
index 35039339e47..629e0318913 100644
--- a/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiUnifier.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/util/psi/patternMatching/KotlinPsiUnifier.kt
@@ -190,8 +190,8 @@ public class KotlinPsiUnifier(
             fun checkArguments(): Status? {
                 val args1 = rc1.getResultingDescriptor()?.getValueParameters()?.map { rc1.getValueArguments()[it] } ?: Collections.emptyList()
                 val args2 = rc2.getResultingDescriptor()?.getValueParameters()?.map { rc2.getValueArguments()[it] } ?: Collections.emptyList()
-                if (args1.size() != args2.size()) return UNMATCHED
-                if (rc1.getCall().getValueArguments().size() != args1.size() || rc2.getCall().getValueArguments().size() != args2.size()) return null
+                if (args1.size != args2.size) return UNMATCHED
+                if (rc1.getCall().getValueArguments().size != args1.size || rc2.getCall().getValueArguments().size != args2.size) return null
 
                 return (args1.asSequence().zip(args2.asSequence())).fold(MATCHED) { s, p ->
                     val (arg1, arg2) = p
@@ -247,7 +247,7 @@ public class KotlinPsiUnifier(
             fun checkTypeArguments(): Status? {
                 val typeArgs1 = rc1.getTypeArguments().toList()
                 val typeArgs2 = rc2.getTypeArguments().toList()
-                if (typeArgs1.size() != typeArgs2.size()) return UNMATCHED
+                if (typeArgs1.size != typeArgs2.size) return UNMATCHED
 
                 for ((typeArg1, typeArg2) in (typeArgs1.zip(typeArgs2))) {
                     if (!matchDescriptors(typeArg1.first, typeArg2.first)) return UNMATCHED
@@ -338,7 +338,7 @@ public class KotlinPsiUnifier(
 
                 val args1 = type1.getArguments()
                 val args2 = type2.getArguments()
-                if (args1.size() != args2.size()) return UNMATCHED
+                if (args1.size != args2.size) return UNMATCHED
                 if (!args1.zip(args2).all {
                     it.first.getProjectionKind() == it.second.getProjectionKind() && matchTypes(it.first.getType(), it.second.getType()) == MATCHED }
                 ) return UNMATCHED
@@ -352,7 +352,7 @@ public class KotlinPsiUnifier(
         private fun matchTypes(types1: Collection<KotlinType>, types2: Collection<KotlinType>): Boolean {
             fun sortTypes(types: Collection<KotlinType>) = types.sortedBy { DescriptorRenderer.DEBUG_TEXT.renderType(it) }
 
-            if (types1.size() != types2.size()) return false
+            if (types1.size != types2.size) return false
             return (sortTypes(types1).zip(sortTypes(types2))).all { matchTypes(it.first, it.second) == MATCHED }
         }
 
@@ -427,7 +427,7 @@ public class KotlinPsiUnifier(
         private fun matchDestructuringDeclarations(e1: KtDestructuringDeclaration, e2: KtDestructuringDeclaration): Boolean {
             val entries1 = e1.getEntries()
             val entries2 = e2.getEntries()
-            if (entries1.size() != entries2.size()) return false
+            if (entries1.size != entries2.size) return false
 
             return entries1.zip(entries2).all { p ->
                 val (entry1, entry2) = p
@@ -487,7 +487,7 @@ public class KotlinPsiUnifier(
             val params2 = desc2.getValueParameters()
             val zippedParams = params1.zip(params2)
             val parametersMatch =
-                    (params1.size() == params2.size()) && zippedParams.all { matchTypes(it.first.getType(), it.second.getType()) == MATCHED }
+                    (params1.size == params2.size) && zippedParams.all { matchTypes(it.first.getType(), it.second.getType()) == MATCHED }
             if (!parametersMatch) return UNMATCHED
 
             zippedParams.forEach { declarationPatternsToTargets.putValue(it.first, it.second) }
@@ -527,7 +527,7 @@ public class KotlinPsiUnifier(
                 matchPair: (Pair<T, T>) -> Boolean
         ): Boolean {
             val zippedParams = declarations1.zip(declarations2)
-            if (declarations1.size() != declarations2.size() || !zippedParams.all { matchPair(it) }) return false
+            if (declarations1.size != declarations2.size || !zippedParams.all { matchPair(it) }) return false
 
             zippedParams.forEach { declarationPatternsToTargets.putValue(it.first, it.second) }
             return true
@@ -580,7 +580,7 @@ public class KotlinPsiUnifier(
             val delegationInfo1 = getDelegationOrderInfo(decl1)
             val delegationInfo2 = getDelegationOrderInfo(decl2)
 
-            if (delegationInfo1.orderInsensitive.size() != delegationInfo2.orderInsensitive.size()) return UNMATCHED
+            if (delegationInfo1.orderInsensitive.size != delegationInfo2.orderInsensitive.size) return UNMATCHED
             outer@
             for (specifier1 in delegationInfo1.orderInsensitive) {
                 for (specifier2 in delegationInfo2.orderInsensitive) {
@@ -599,7 +599,7 @@ public class KotlinPsiUnifier(
 
             val sortedMembers1 = resolveAndSortDeclarationsByDescriptor(membersInfo1.orderInsensitive)
             val sortedMembers2 = resolveAndSortDeclarationsByDescriptor(membersInfo2.orderInsensitive)
-            if ((sortedMembers1.size() != sortedMembers2.size())) return UNMATCHED
+            if ((sortedMembers1.size != sortedMembers2.size)) return UNMATCHED
             if (sortedMembers1.zip(sortedMembers2).any {
                 val (d1, d2) = it
                 (matchDeclarations(d1.first, d2.first, d1.second, d2.second) ?: doUnify(d1.first, d2.first)) == UNMATCHED
@@ -774,7 +774,7 @@ public class KotlinPsiUnifier(
 
             val targetElements = target.elements
             val patternElements = pattern.elements
-            if (targetElements.size() != patternElements.size()) return UNMATCHED
+            if (targetElements.size != patternElements.size) return UNMATCHED
 
             return (targetElements.asSequence().zip(patternElements.asSequence())).fold(MATCHED) { s, p ->
                 if (s != UNMATCHED) s and doUnify(p.first, p.second) else s
@@ -898,7 +898,7 @@ public class KotlinPsiUnifier(
         return with(Context(target, pattern)) {
             val status = doUnify(target, pattern)
             when {
-                substitution.size() != descriptorToParameter.size() ->
+                substitution.size != descriptorToParameter.size ->
                     Unmatched
                 status == MATCHED -> {
                     val targetRange = targetSubstringInfo?.createExpression()?.toRange() ?: target
diff --git a/idea/src/org/jetbrains/kotlin/idea/versions/KotlinAbiVersionIndexBase.kt b/idea/src/org/jetbrains/kotlin/idea/versions/KotlinAbiVersionIndexBase.kt
index 2473d958fff..d8e74a0660f 100644
--- a/idea/src/org/jetbrains/kotlin/idea/versions/KotlinAbiVersionIndexBase.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/versions/KotlinAbiVersionIndexBase.kt
@@ -45,7 +45,7 @@ abstract class KotlinAbiVersionIndexBase<T>(private val classOfIndex: Class<T>)
 
         override fun save(output: DataOutput, value: BinaryVersion) {
             val array = value.toArray()
-            DataInputOutputUtil.writeINT(output, array.size())
+            DataInputOutputUtil.writeINT(output, array.size)
             for (number in array) {
                 DataInputOutputUtil.writeINT(output, number)
             }
@@ -61,7 +61,7 @@ abstract class KotlinAbiVersionIndexBase<T>(private val classOfIndex: Class<T>)
             body()
         }
         catch (e: Throwable) {
-            LOG.warn("Could not index ABI version for file " + inputData.file + ": " + e.getMessage())
+            LOG.warn("Could not index ABI version for file " + inputData.file + ": " + e.message)
         }
     }
 }
diff --git a/idea/tests/org/jetbrains/kotlin/DataFlowValueRenderingTest.kt b/idea/tests/org/jetbrains/kotlin/DataFlowValueRenderingTest.kt
index 4ebebf86c1e..8da3f6510a7 100644
--- a/idea/tests/org/jetbrains/kotlin/DataFlowValueRenderingTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/DataFlowValueRenderingTest.kt
@@ -48,7 +48,7 @@ public abstract class AbstractDataFlowValueRenderingTest: KotlinLightCodeInsight
         val expression = element.getStrictParentOfType<KtExpression>()!!
         val info = expression.analyze().getDataFlowInfo(expression)
 
-        val allValues = (info.getCompleteTypeInfo().keySet() + info.getCompleteNullabilityInfo().keySet()).toSet()
+        val allValues = (info.getCompleteTypeInfo().keySet() + info.getCompleteNullabilityInfo().keys).toSet()
         val actual = allValues.mapNotNull { renderDataFlowValue(it) }.sorted().joinToString("\n")
 
         KotlinTestUtils.assertEqualsToFile(File(FileUtil.getNameWithoutExtension(fileName) + ".txt"), actual)
diff --git a/idea/tests/org/jetbrains/kotlin/addImport/AbstractAddImportTest.kt b/idea/tests/org/jetbrains/kotlin/addImport/AbstractAddImportTest.kt
index 3079875ed11..ac261b35e6a 100644
--- a/idea/tests/org/jetbrains/kotlin/addImport/AbstractAddImportTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/addImport/AbstractAddImportTest.kt
@@ -36,7 +36,7 @@ public abstract class AbstractAddImportTest : AbstractImportsTest() {
         var filter: (DeclarationDescriptor) -> Boolean = { true }
         if (descriptorName.startsWith("class:")) {
             filter = { it is ClassDescriptor }
-            descriptorName = descriptorName.substring("class:".length()).trim()
+            descriptorName = descriptorName.substring("class:".length).trim()
         }
 
         val descriptors = file.resolveImportReference(FqName(descriptorName)).filter(filter)
@@ -45,7 +45,7 @@ public abstract class AbstractAddImportTest : AbstractImportsTest() {
             descriptors.isEmpty() ->
                 error("No descriptor $descriptorName found")
 
-            descriptors.size() > 1 ->
+            descriptors.size > 1 ->
                 error("Multiple descriptors found:\n    " + descriptors.map { DescriptorRenderer.FQ_NAMES_IN_TYPES.render(it) }.joinToString("\n    "))
 
             else -> {
diff --git a/idea/tests/org/jetbrains/kotlin/asJava/LightClassesClasspathSortingTest.kt b/idea/tests/org/jetbrains/kotlin/asJava/LightClassesClasspathSortingTest.kt
index 5fe20e8817d..4872d369d63 100644
--- a/idea/tests/org/jetbrains/kotlin/asJava/LightClassesClasspathSortingTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/asJava/LightClassesClasspathSortingTest.kt
@@ -43,7 +43,7 @@ class LightClassesClasspathSortingTest : KotlinCodeInsightTestCase() {
         getModule().configureAs(getProjectDescriptor(dirName))
 
         val testDirRoot = File(getTestDataPath())
-        val filePaths = File(testDirRoot, dirName).listFiles().map { it.relativeTo(testDirRoot) }.toArrayList().toTypedArray()
+        val filePaths = File(testDirRoot, dirName).listFiles().map { it.toRelativeString(testDirRoot) }.toTypedArray()
         configureByFiles(null, *filePaths)
 
         checkLightClassBeforeDecompiled(fqName)
diff --git a/idea/tests/org/jetbrains/kotlin/findUsages/KotlinFindUsagesWithLibraryCustomTest.kt b/idea/tests/org/jetbrains/kotlin/findUsages/KotlinFindUsagesWithLibraryCustomTest.kt
index c5cdfb6d48b..7b2195d4d18 100644
--- a/idea/tests/org/jetbrains/kotlin/findUsages/KotlinFindUsagesWithLibraryCustomTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/findUsages/KotlinFindUsagesWithLibraryCustomTest.kt
@@ -27,6 +27,6 @@ public class KotlinFindUsagesWithLibraryCustomTest : AbstractKotlinFindUsagesWit
         val indexOf = libraryFile.getText().indexOf("localClassProperty")
         val jetParameter = libraryFile.findElementAt(indexOf)!!.getStrictParentOfType<KtParameter>()!!
         val usages = findUsages(jetParameter.getOriginalElement(), null, false)
-        assertEquals(2, usages.size())
+        assertEquals(2, usages.size)
     }
 }
\ No newline at end of file
diff --git a/idea/tests/org/jetbrains/kotlin/idea/RegisteredFindersTest.kt b/idea/tests/org/jetbrains/kotlin/idea/RegisteredFindersTest.kt
index 44cc11a0220..c0b9ba7b067 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/RegisteredFindersTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/RegisteredFindersTest.kt
@@ -34,7 +34,7 @@ public class RegisteredFindersTest : KotlinLightCodeInsightFixtureTestCase() {
                 val name = finder.javaClass.getSimpleName()
                 val removed = expectedFindersNames.remove(name)
                 Assert.assertTrue("Unknown finder found: $finder, class name: $name, search in $expectedFindersNames.\n" +
-                                  "Consider updating ${javaClass<KotlinJavaPsiFacade>()}",
+                                  "Consider updating ${KotlinJavaPsiFacade::class.java}",
                                   removed)
             }
         }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractInspectionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractInspectionTest.kt
index e85fa01df6d..4f5c99bd37c 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractInspectionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractInspectionTest.kt
@@ -71,13 +71,13 @@ public abstract class AbstractInspectionTest : KotlinLightCodeInsightFixtureTest
             setTestDataPath("${KotlinTestUtils.getHomeDirectory()}/$srcDir")
 
             val afterFiles = srcDir.listFiles { it -> it.name == "inspectionData" }?.single()?.listFiles { it -> it.extension == "after" } ?: emptyArray()
-            val psiFiles = srcDir.walkTopDown().treeFilter { it.name != "inspectionData" }.mapNotNull {
+            val psiFiles = srcDir.walkTopDown().onEnter { it.name != "inspectionData" }.mapNotNull {
                 file ->
                 if (file.isDirectory) {
                      null
                 }
                 else if (file.extension != "kt") {
-                    val filePath = file.relativeTo(srcDir).replace('\\', '/')
+                    val filePath = file.relativeToFile(srcDir).invariantSeparatorsPath
                     configureByFile(filePath)
                 }
                 else {
diff --git a/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractOverrideImplementTest.kt b/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractOverrideImplementTest.kt
index 1d9fdc0e3de..1e5395e1036 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractOverrideImplementTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/codeInsight/AbstractOverrideImplementTest.kt
@@ -122,7 +122,7 @@ public abstract class AbstractOverrideImplementTest : KotlinLightCodeInsightFixt
 
     private fun doOverrideImplement(handler: OverrideImplementMembersHandler, memberToOverride: String?) {
         val elementAtCaret = myFixture.file.findElementAt(myFixture.editor.caretModel.offset)
-        val classOrObject = PsiTreeUtil.getParentOfType(elementAtCaret, javaClass<KtClassOrObject>())
+        val classOrObject = PsiTreeUtil.getParentOfType(elementAtCaret, KtClassOrObject::class.java)
                             ?: error("Caret should be inside class or object")
 
         val chooserObjects = handler.collectMembersToGenerate(classOrObject)
@@ -133,7 +133,7 @@ public abstract class AbstractOverrideImplementTest : KotlinLightCodeInsightFixt
                     !KotlinBuiltIns.isAny(it)
                 } ?: true
             }
-            assertEquals(1, filtered.size(), "Invalid number of available chooserObjects for override")
+            assertEquals(1, filtered.size, "Invalid number of available chooserObjects for override")
             filtered.single()
         }
         else {
@@ -157,7 +157,7 @@ public abstract class AbstractOverrideImplementTest : KotlinLightCodeInsightFixt
 
     private fun doMultiOverrideImplement(handler: OverrideImplementMembersHandler) {
         val elementAtCaret = myFixture.file.findElementAt(myFixture.editor.caretModel.offset)
-        val classOrObject = PsiTreeUtil.getParentOfType(elementAtCaret, javaClass<KtClassOrObject>())
+        val classOrObject = PsiTreeUtil.getParentOfType(elementAtCaret, KtClassOrObject::class.java)
                             ?: error("Caret should be inside class or object")
 
         val chooserObjects = handler.collectMembersToGenerate(classOrObject).sortedBy { it.descriptor.name.asString() + " in " + it.immediateSuper.containingDeclaration.name.asString() }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/codeInsight/generate/AbstractCodeInsightActionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/codeInsight/generate/AbstractCodeInsightActionTest.kt
index 58b311cc61e..ad096f0248c 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/codeInsight/generate/AbstractCodeInsightActionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/codeInsight/generate/AbstractCodeInsightActionTest.kt
@@ -86,7 +86,7 @@ abstract class AbstractCodeInsightActionTest : KotlinLightCodeInsightFixtureTest
             }
         }
         catch (e: CommonRefactoringUtil.RefactoringErrorHintException) {
-            KotlinTestUtils.assertEqualsToFile(conflictFile, e.getMessage()!!)
+            KotlinTestUtils.assertEqualsToFile(conflictFile, e.message!!)
         }
         finally {
             ConfigLibraryUtil.unconfigureLibrariesByDirective(myModule, fileText)
diff --git a/idea/tests/org/jetbrains/kotlin/idea/coverage/AbstractKotlinCoverageOutputFilesTest.kt b/idea/tests/org/jetbrains/kotlin/idea/coverage/AbstractKotlinCoverageOutputFilesTest.kt
index c615e03f19f..338f123b5ef 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/coverage/AbstractKotlinCoverageOutputFilesTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/coverage/AbstractKotlinCoverageOutputFilesTest.kt
@@ -55,7 +55,7 @@ private fun createEmptyFile(dir: VirtualFile, relativePath: String) {
     var currentDir = dir
     val segments = relativePath.split('/')
     segments.forEachIndexed { i, s ->
-        if (i < segments.size() - 1) {
+        if (i < segments.size - 1) {
             currentDir = currentDir.createChildDirectory(null, s)
         } else {
             currentDir.createChildData(null, s)
diff --git a/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractEditorForEvaluateExpressionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractEditorForEvaluateExpressionTest.kt
index 27c766e44cd..b291737fbaa 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractEditorForEvaluateExpressionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/AbstractEditorForEvaluateExpressionTest.kt
@@ -126,9 +126,9 @@ private fun JavaCodeInsightTestFixture.configureByCodeFragment(filePath: String)
     val typeStr = InTextDirectivesUtils.findStringWithPrefixes(getFile().getText(), "// ${ExpectedCompletionUtils.RUNTIME_TYPE} ")
     if (typeStr != null) {
         file.putCopyableUserData(KtCodeFragment.RUNTIME_TYPE_EVALUATOR, {
-            val codeFragment = KtPsiFactory(getProject()).createBlockCodeFragment("val xxx: $typeStr" , PsiTreeUtil.getParentOfType(elementAt, javaClass<KtElement>()))
+            val codeFragment = KtPsiFactory(getProject()).createBlockCodeFragment("val xxx: $typeStr" , PsiTreeUtil.getParentOfType(elementAt, KtElement::class.java))
             val context = codeFragment.analyzeFully()
-            val typeReference: KtTypeReference = PsiTreeUtil.getChildOfType(codeFragment.getContentElement().getFirstChild(), javaClass())!!
+            val typeReference: KtTypeReference = PsiTreeUtil.getChildOfType(codeFragment.getContentElement().getFirstChild(), KtTypeReference::class.java)!!
             context[BindingContext.TYPE, typeReference]
         })
     }
@@ -140,7 +140,7 @@ private fun createCodeFragment(filePath: String, contextElement: PsiElement): Kt
     val fileForFragment = File(filePath + ".fragment")
     val codeFragmentText = FileUtil.loadFile(fileForFragment, true).trim()
     val psiFactory = KtPsiFactory(contextElement.getProject())
-    if (fileForFragment.readLines().size() == 1) {
+    if (fileForFragment.readLines().size == 1) {
         return psiFactory.createExpressionCodeFragment(
                 codeFragmentText,
                 KotlinCodeFragmentFactory.getContextElement(contextElement)
diff --git a/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt b/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt
index 94e13b6ac17..0705e431e64 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt
@@ -78,7 +78,7 @@ public abstract class AbstractNavigateToLibrarySourceTest : KotlinCodeInsightTes
 
             refs.forEach { referenceContainersToReferences.addReference(it) }
         }
-        return referenceContainersToReferences.values()
+        return referenceContainersToReferences.values
     }
 
     private fun MutableMap<PsiElement, KtReference>.addReference(ref: KtReference) {
diff --git a/idea/tests/org/jetbrains/kotlin/idea/folding/FoldingAfterOptimizeImportsTest.kt b/idea/tests/org/jetbrains/kotlin/idea/folding/FoldingAfterOptimizeImportsTest.kt
index 7908ac2a978..b6cd10a31b7 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/folding/FoldingAfterOptimizeImportsTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/folding/FoldingAfterOptimizeImportsTest.kt
@@ -64,7 +64,7 @@ class FoldingAfterOptimizeImportsTest : AbstractKotlinFoldingTest() {
         fixture.doHighlighting()
         val model = getEditor().getFoldingModel()
         val foldingRegions = model.getAllFoldRegions()
-        assert(foldingRegions.size() >= number) { "There is no enough folding regions in file: in file - ${foldingRegions.size()} , expected = ${number}" }
+        assert(foldingRegions.size >= number) { "There is no enough folding regions in file: in file - ${foldingRegions.size} , expected = ${number}" }
         return foldingRegions[number]
     }
 
diff --git a/idea/tests/org/jetbrains/kotlin/idea/highlighter/AbstractUsageHighlightingTest.kt b/idea/tests/org/jetbrains/kotlin/idea/highlighter/AbstractUsageHighlightingTest.kt
index acd5cc22c58..664833015ac 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/highlighter/AbstractUsageHighlightingTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/highlighter/AbstractUsageHighlightingTest.kt
@@ -40,7 +40,7 @@ public abstract class AbstractUsageHighlightingTest: KotlinLightCodeInsightFixtu
         assert(caret != -1) { "Caret marker '$CARET_TAG' expected" }
 
         WriteCommandAction.runWriteCommandAction(myFixture.getProject()) {
-            document.deleteString(caret, caret + CARET_TAG.length())
+            document.deleteString(caret, caret + CARET_TAG.length)
         }
 
         getEditor().getCaretModel().moveToOffset(caret)
@@ -52,8 +52,8 @@ public abstract class AbstractUsageHighlightingTest: KotlinLightCodeInsightFixtu
             var startOffset = highlighter.getStartOffset()
             var endOffset = highlighter.getEndOffset()
 
-            if (startOffset > caret) startOffset += CARET_TAG.length()
-            if (endOffset > caret) endOffset += CARET_TAG.length()
+            if (startOffset > caret) startOffset += CARET_TAG.length
+            if (endOffset > caret) endOffset += CARET_TAG.length
 
             HighlightInfo.newHighlightInfo(HighlightInfoType.INFORMATION).range(startOffset, endOffset).create()
         }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/highlighter/NoErrorsInStdlibTest.kt b/idea/tests/org/jetbrains/kotlin/idea/highlighter/NoErrorsInStdlibTest.kt
index 43cdc60c5df..0fa3a7269ea 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/highlighter/NoErrorsInStdlibTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/highlighter/NoErrorsInStdlibTest.kt
@@ -49,12 +49,12 @@ public class NoErrorsInStdlibTest : KotlinLightCodeInsightFixtureTestCase() {
                     val errors = bindingContext.getDiagnostics().all().filter { it.getSeverity() == Severity.ERROR }
 
                     if (errors.isNotEmpty()) {
-                        System.err.println("${psiFile.getName()}: ${errors.size()} errors")
+                        System.err.println("${psiFile.getName()}: ${errors.size} errors")
                         AnalyzerWithCompilerReport.reportDiagnostics(
                                 bindingContext.getDiagnostics(), PrintingMessageCollector.PLAIN_TEXT_TO_SYSTEM_ERR
                         )
 
-                        totalErrors += errors.size()
+                        totalErrors += errors.size
                     }
                 }
             }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/inspections/KotlinCleanupInspectionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/inspections/KotlinCleanupInspectionTest.kt
index 9529249fa50..6858a65a33b 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/inspections/KotlinCleanupInspectionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/inspections/KotlinCleanupInspectionTest.kt
@@ -32,7 +32,7 @@ class KotlinCleanupInspectionTest(): KotlinLightCodeInsightFixtureTestCase() {
     override fun getProjectDescriptor(): LightProjectDescriptor = KotlinWithJdkAndRuntimeLightProjectDescriptor.INSTANCE
 
     private fun doTest(result: String, vararg files: String) {
-        myFixture.enableInspections(javaClass<KotlinCleanupInspection>())
+        myFixture.enableInspections(KotlinCleanupInspection::class.java)
         myFixture.configureByFiles(*files)
 
         val project = myFixture.getProject()
diff --git a/idea/tests/org/jetbrains/kotlin/idea/intentions/AbstractMultiFileIntentionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/intentions/AbstractMultiFileIntentionTest.kt
index 0fe61e35a6a..9839a20f5c8 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/intentions/AbstractMultiFileIntentionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/intentions/AbstractMultiFileIntentionTest.kt
@@ -72,7 +72,7 @@ public abstract class AbstractMultiFileIntentionTest : KotlinMultiFileTestCase()
                        assert(conflictFile == null) { "Conflict file $conflictFile should not exist" }
                    }
                    catch (e: CommonRefactoringUtil.RefactoringErrorHintException) {
-                       KotlinTestUtils.assertEqualsToFile(File(conflictFile!!.path), e.getMessage()!!)
+                       KotlinTestUtils.assertEqualsToFile(File(conflictFile!!.path), e.message!!)
                    }
                    finally {
                        PsiDocumentManager.getInstance(getProject()!!).commitAllDocuments()
diff --git a/idea/tests/org/jetbrains/kotlin/idea/parameterInfo/AbstractParameterInfoTest.kt b/idea/tests/org/jetbrains/kotlin/idea/parameterInfo/AbstractParameterInfoTest.kt
index 2663353fcc8..be2bff367f2 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/parameterInfo/AbstractParameterInfoTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/parameterInfo/AbstractParameterInfoTest.kt
@@ -47,7 +47,7 @@ abstract class AbstractParameterInfoTest : LightCodeInsightFixtureTestCase() {
 
         val lastChild = file.allChildren.filter { it !is PsiWhiteSpace }.last()
         val expectedResultText = when (lastChild.node.elementType) {
-            KtTokens.BLOCK_COMMENT -> lastChild.text.substring(2, lastChild.text.length() - 2).trim()
+            KtTokens.BLOCK_COMMENT -> lastChild.text.substring(2, lastChild.text.length - 2).trim()
             KtTokens.EOL_COMMENT -> lastChild.text.substring(2).trim()
             else -> error("Unexpected last file child")
         }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/refactoring/AbstractMemberPullPushTest.kt b/idea/tests/org/jetbrains/kotlin/idea/refactoring/AbstractMemberPullPushTest.kt
index 0b81fd88633..c6dbadbed41 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/refactoring/AbstractMemberPullPushTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/refactoring/AbstractMemberPullPushTest.kt
@@ -87,7 +87,7 @@ public abstract class AbstractMemberPullPushTest : KotlinLightCodeInsightFixture
         catch(e: Exception) {
             val message = when (e) {
                 is BaseRefactoringProcessor.ConflictsInTestsException -> e.messages.sorted().joinToString("\n")
-                is CommonRefactoringUtil.RefactoringErrorHintException -> e.getMessage()!!
+                is CommonRefactoringUtil.RefactoringErrorHintException -> e.message!!
                 else -> throw e
             }
             KotlinTestUtils.assertEqualsToFile(conflictFile, message)
diff --git a/idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/AbstractExtractionTest.kt b/idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/AbstractExtractionTest.kt
index 576615f7b86..28fa3d69cac 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/AbstractExtractionTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/AbstractExtractionTest.kt
@@ -251,7 +251,7 @@ public abstract class AbstractExtractionTest() : KotlinLightCodeInsightFixtureTe
                 if (it.isNotEmpty()) {
                     @Suppress("CAST_NEVER_SUCCEEDS")
                     val args = it.map { it.toBoolean() }.toTypedArray() as Array<Any?>
-                    javaClass<ExtractionOptions>().getConstructors().first { it.getParameterTypes().size() == args.size() }.newInstance(*args) as ExtractionOptions
+                    ExtractionOptions::class.java.getConstructors().first { it.getParameterTypes().size == args.size }.newInstance(*args) as ExtractionOptions
                 } else ExtractionOptions.DEFAULT
             }
 
@@ -281,10 +281,10 @@ public abstract class AbstractExtractionTest() : KotlinLightCodeInsightFixtureTe
                                 it.getParameterTypeCandidates(false).map { renderer.renderType(it) }.joinToString(", ", "[", "]")
                             }.joinToString()
 
-                            if (actualNames.size() != 1 || expectedNames.isNotEmpty()) {
+                            if (actualNames.size != 1 || expectedNames.isNotEmpty()) {
                                 assertEquals(expectedNames, actualNames, "Expected names mismatch.")
                             }
-                            if (actualReturnTypes.size() != 1 || expectedReturnTypes.isNotEmpty()) {
+                            if (actualReturnTypes.size != 1 || expectedReturnTypes.isNotEmpty()) {
                                 assertEquals(expectedReturnTypes, actualReturnTypes, "Expected return types mismatch.")
                             }
                             assertEquals("Expected descriptors mismatch.", expectedDescriptors, actualDescriptors)
diff --git a/idea/tests/org/jetbrains/kotlin/idea/refactoring/nameSuggester/KotlinNameSuggesterTest.kt b/idea/tests/org/jetbrains/kotlin/idea/refactoring/nameSuggester/KotlinNameSuggesterTest.kt
index fc27850a76f..2fa4ccbf9a8 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/refactoring/nameSuggester/KotlinNameSuggesterTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/refactoring/nameSuggester/KotlinNameSuggesterTest.kt
@@ -97,7 +97,7 @@ public class KotlinNameSuggesterTest : LightCodeInsightFixtureTestCase() {
             })
         }
         catch (e: KotlinRefactoringUtil.IntroduceRefactoringException) {
-            throw AssertionError("Failed to find expression: " + e.getMessage())
+            throw AssertionError("Failed to find expression: " + e.message)
         }
         finally {
             if (withRuntime) {
diff --git a/idea/tests/org/jetbrains/kotlin/idea/refactoring/pullUp/AbstractPullUpTest.kt b/idea/tests/org/jetbrains/kotlin/idea/refactoring/pullUp/AbstractPullUpTest.kt
index 446ee015823..478e18efa14 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/refactoring/pullUp/AbstractPullUpTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/refactoring/pullUp/AbstractPullUpTest.kt
@@ -57,7 +57,7 @@ public abstract class AbstractPullUpTest : AbstractMemberPullPushTest() {
     protected fun doJavaTest(path: String) {
         doTest(path) { file ->
             val elementAt = getFile().findElementAt(getEditor().caretModel.offset)
-            val sourceClass = PsiTreeUtil.getParentOfType(elementAt, javaClass<PsiClass>())!!
+            val sourceClass = PsiTreeUtil.getParentOfType(elementAt, PsiClass::class.java)!!
 
             val targetClassName = getTargetClassName(file)
             val superClasses = RefactoringHierarchyUtil.createBasesList(sourceClass, false, true)
diff --git a/idea/tests/org/jetbrains/kotlin/idea/refactoring/rename/AbstractRenameTest.kt b/idea/tests/org/jetbrains/kotlin/idea/refactoring/rename/AbstractRenameTest.kt
index 8ac96008586..c5e06c42461 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/refactoring/rename/AbstractRenameTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/refactoring/rename/AbstractRenameTest.kt
@@ -129,7 +129,7 @@ public abstract class AbstractRenameTest : KotlinMultiFileTestCase() {
         catch (e : Exception) {
             if (e !is RefactoringErrorHintException && e !is ConflictsInTestsException) throw e
 
-            val hintExceptionUnquoted = StringUtil.unquoteString(e.getMessage()!!)
+            val hintExceptionUnquoted = StringUtil.unquoteString(e.message!!)
             if (hintDirective != null) {
                 Assert.assertEquals(hintDirective, hintExceptionUnquoted)
             }
@@ -153,11 +153,11 @@ public abstract class AbstractRenameTest : KotlinMultiFileTestCase() {
 
             val toRename = if (renameParamsObject["byRef"]?.getAsBoolean() ?: false) {
                 val editor = createEditor(mainFile)
-                editor.getCaretModel().moveToOffset(marker + MARKER_TEXT.length())
+                editor.getCaretModel().moveToOffset(marker + MARKER_TEXT.length)
                 TargetElementUtilBase.findTargetElement(editor, TargetElementUtilBase.getInstance().getAllAccepted())!!
             }
             else {
-                psiFile.findElementAt(marker + MARKER_TEXT.length())!!.getNonStrictParentOfType<PsiNamedElement>()!!
+                psiFile.findElementAt(marker + MARKER_TEXT.length)!!.getNonStrictParentOfType<PsiNamedElement>()!!
             }
             val substitution = RenamePsiElementProcessor.forElement(toRename).substituteElementToRename(toRename, null)
 
@@ -228,7 +228,7 @@ public abstract class AbstractRenameTest : KotlinMultiFileTestCase() {
             val fileFqn = jetFile.getPackageFqName()
             Assert.assertTrue("File '${mainFilePath}' should have package containing ${fqn}", fileFqn.isSubpackageOf(fqn))
 
-            val packageSegment = jetFile.getPackageDirective()!!.getPackageNames()[fqn.pathSegments().size() - 1]
+            val packageSegment = jetFile.getPackageDirective()!!.getPackageNames()[fqn.pathSegments().size - 1]
             val segmentReference = packageSegment.mainReference
 
             val psiElement = segmentReference.resolve()!!
diff --git a/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractPartialBodyResolveTest.kt b/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractPartialBodyResolveTest.kt
index c9d5af634a7..e85c311ded0 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractPartialBodyResolveTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractPartialBodyResolveTest.kt
@@ -72,7 +72,7 @@ public abstract class AbstractPartialBodyResolveTest : KotlinLightCodeInsightFix
         val editor = myFixture.getEditor()
         val selectionModel = editor.getSelectionModel()
         val expression = if (selectionModel.hasSelection()) {
-            PsiTreeUtil.findElementOfClassAtRange(file, selectionModel.getSelectionStart(), selectionModel.getSelectionEnd(), javaClass<KtExpression>())
+            PsiTreeUtil.findElementOfClassAtRange(file, selectionModel.getSelectionStart(), selectionModel.getSelectionEnd(), KtExpression::class.java)
                 ?: error("No JetExpression at selection range")
         }
         else {
diff --git a/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveInLibrarySourcesTest.kt b/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveInLibrarySourcesTest.kt
index a6ca6b88a60..ce2c4eda940 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveInLibrarySourcesTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveInLibrarySourcesTest.kt
@@ -37,7 +37,7 @@ public abstract class AbstractReferenceResolveInLibrarySourcesTest : KotlinLight
         val expectedResolveData = AbstractReferenceResolveTest.readResolveData(fixture.getFile()!!.getText(), 0)
 
         val gotoData = NavigationTestUtils.invokeGotoImplementations(fixture.getEditor(), fixture.getFile())!!
-        Assert.assertEquals("Single target expected for origianl file", 1, gotoData.targets.size())
+        Assert.assertEquals("Single target expected for origianl file", 1, gotoData.targets.size)
 
         val testedPsiElement = gotoData.targets[0].getNavigationElement()
         val testedElementFile = testedPsiElement.getContainingFile()!!
diff --git a/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveTest.kt b/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveTest.kt
index a6985cd4491..c77b823ea97 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/resolve/AbstractReferenceResolveTest.kt
@@ -83,7 +83,7 @@ public abstract class AbstractReferenceResolveTest : KotlinLightPlatformCodeInsi
 
     private fun forEachCaret(action: (index: Int, offset: Int) -> Unit) {
         val offsets = myFixture.getEditor().getCaretModel().getAllCarets().map { it.getOffset() }
-        val singleCaret = offsets.size() == 1
+        val singleCaret = offsets.size == 1
         for ((index, offset) in offsets.withIndex()) {
             action(if (singleCaret) -1 else index + 1, offset)
         }
@@ -107,7 +107,7 @@ public abstract class AbstractReferenceResolveTest : KotlinLightPlatformCodeInsi
                 referenceToString = "<empty>"
             }
             else {
-                assertTrue(refs.size() == 1, "Must be a single ref: $refs.\nUse $MULTIRESOLVE if you need multiple refs\nUse $REF_EMPTY for an unresolved reference")
+                assertTrue(refs.size == 1, "Must be a single ref: $refs.\nUse $MULTIRESOLVE if you need multiple refs\nUse $REF_EMPTY for an unresolved reference")
                 referenceToString = refs.get(0)
                 Assert.assertNotNull("Test data wasn't found, use \"// REF: \" directive", referenceToString)
             }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/run/RunConfigurationTest.kt b/idea/tests/org/jetbrains/kotlin/idea/run/RunConfigurationTest.kt
index 3bc125561ea..3d197320bb8 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/run/RunConfigurationTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/run/RunConfigurationTest.kt
@@ -185,7 +185,7 @@ class RunConfigurationTest: KotlinCodeInsightTestCase() {
                             val text = comment.getText() ?: return
                             if (!text.startsWith(RUN_PREFIX)) return
 
-                            val expectedClass = text.substring(RUN_PREFIX.length()).trim()
+                            val expectedClass = text.substring(RUN_PREFIX.length).trim()
                             if (expectedClass.isNotEmpty()) expectedClasses.add(expectedClass)
 
                             val dataContext = MapDataContext()
diff --git a/idea/tests/org/jetbrains/kotlin/idea/structureView/AbstractKotlinFileStructureTest.kt b/idea/tests/org/jetbrains/kotlin/idea/structureView/AbstractKotlinFileStructureTest.kt
index f5e5767eadd..7890645fb81 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/structureView/AbstractKotlinFileStructureTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/structureView/AbstractKotlinFileStructureTest.kt
@@ -59,7 +59,7 @@ public abstract class AbstractKotlinFileStructureTest : KotlinLightCodeInsightFi
         val fileText = FileUtil.loadFile(File(getTestDataPath(), fileName()), true)
 
         val withInherited = InTextDirectivesUtils.isDirectiveDefined(fileText, "WITH_INHERITED")
-        setTreeActionState(javaClass<KotlinInheritedMembersNodeProvider>(), withInherited)
+        setTreeActionState(KotlinInheritedMembersNodeProvider::class.java, withInherited)
     }
 
     public fun FileStructurePopup.update() {
diff --git a/idea/tests/org/jetbrains/kotlin/idea/stubs/DebugTextByStubTest.kt b/idea/tests/org/jetbrains/kotlin/idea/stubs/DebugTextByStubTest.kt
index 22283872c4f..73482dc34ad 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/stubs/DebugTextByStubTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/stubs/DebugTextByStubTest.kt
@@ -59,7 +59,7 @@ public class DebugTextByStubTest : LightCodeInsightFixtureTestCase() {
         val (file, tree) = createFileAndStubTree(text)
         val function = tree.findChildStubByType(KtStubElementTypes.FUNCTION)
         val psi = KtNamedFunction(function as KotlinFunctionStub)
-        Assert.assertEquals("STUB: " + file.findChildByClass(javaClass<KtNamedFunction>())!!.getText(), psi.getDebugText())
+        Assert.assertEquals("STUB: " + file.findChildByClass(KtNamedFunction::class.java)!!.getText(), psi.getDebugText())
     }
 
     fun typeReference(text: String) {
@@ -69,7 +69,7 @@ public class DebugTextByStubTest : LightCodeInsightFixtureTestCase() {
         val valueParameter = parameterList.findChildStubByType(KtStubElementTypes.VALUE_PARAMETER)!!
         val typeReferenceStub = valueParameter.findChildStubByType(KtStubElementTypes.TYPE_REFERENCE)
         val psiFromStub = KtTypeReference(typeReferenceStub as KotlinPlaceHolderStub)
-        val typeReferenceByPsi = file.findChildByClass(javaClass<KtNamedFunction>())!!.getValueParameters()[0].getTypeReference()
+        val typeReferenceByPsi = file.findChildByClass(KtNamedFunction::class.java)!!.getValueParameters()[0].getTypeReference()
         Assert.assertEquals(typeReferenceByPsi!!.getText(), psiFromStub.getDebugText())
     }
 
@@ -77,7 +77,7 @@ public class DebugTextByStubTest : LightCodeInsightFixtureTestCase() {
         val (file, tree) = createFileAndStubTree(text)
         val clazz = tree.findChildStubByType(KtStubElementTypes.CLASS)!!
         val psiFromStub = KtClass(clazz as KotlinClassStub)
-        val classByPsi = file.findChildByClass(javaClass<KtClass>())
+        val classByPsi = file.findChildByClass(KtClass::class.java)
         val toCheckAgainst = "STUB: " + (expectedText ?: classByPsi!!.getText())
         Assert.assertEquals(toCheckAgainst, psiFromStub.getDebugText())
         if (expectedText != null) {
@@ -89,7 +89,7 @@ public class DebugTextByStubTest : LightCodeInsightFixtureTestCase() {
         val (file, tree) = createFileAndStubTree(text)
         val obj = tree.findChildStubByType(KtStubElementTypes.OBJECT_DECLARATION)!!
         val psiFromStub = KtObjectDeclaration(obj as KotlinObjectStub)
-        val objectByPsi = file.findChildByClass(javaClass<KtObjectDeclaration>())
+        val objectByPsi = file.findChildByClass(KtObjectDeclaration::class.java)
         val toCheckAgainst = "STUB: " + (expectedText ?: objectByPsi!!.getText())
         Assert.assertEquals(toCheckAgainst, psiFromStub.getDebugText())
     }
@@ -98,7 +98,7 @@ public class DebugTextByStubTest : LightCodeInsightFixtureTestCase() {
         val (file, tree) = createFileAndStubTree(text)
         val property = tree.findChildStubByType(KtStubElementTypes.PROPERTY)!!
         val psiFromStub = KtProperty(property as KotlinPropertyStub)
-        val propertyByPsi = file.findChildByClass(javaClass<KtProperty>())
+        val propertyByPsi = file.findChildByClass(KtProperty::class.java)
         val toCheckAgainst = "STUB: " + (expectedText ?: propertyByPsi!!.getText())
         Assert.assertEquals(toCheckAgainst, psiFromStub.getDebugText())
     }
diff --git a/idea/tests/org/jetbrains/kotlin/psi/injection/StringInjectionHostTest.kt b/idea/tests/org/jetbrains/kotlin/psi/injection/StringInjectionHostTest.kt
index 3fc03a1e335..abae31f5a9e 100644
--- a/idea/tests/org/jetbrains/kotlin/psi/injection/StringInjectionHostTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/psi/injection/StringInjectionHostTest.kt
@@ -133,13 +133,13 @@ public class StringInjectionHostTest: KotlinLiteFixture() {
             val chars = StringBuilder(prefix)
             val range = rangeInHost ?: escaper.getRelevantTextRange()
             assertTrue(escaper.decode(range, chars))
-            assertEquals(decoded, chars.substring(prefix.length()))
+            assertEquals(decoded, chars.substring(prefix.length))
             val extendedOffsets = HashMap(targetToSourceOffsets)
-            val beforeStart = targetToSourceOffsets.keySet().min()!! - 1
+            val beforeStart = targetToSourceOffsets.keys.min()!! - 1
             if (beforeStart >= 0) {
                 extendedOffsets[beforeStart] = -1
             }
-            extendedOffsets[targetToSourceOffsets.keySet().max()!! + 1] = -1
+            extendedOffsets[targetToSourceOffsets.keys.max()!! + 1] = -1
             for ((target, source) in extendedOffsets) {
                 assertEquals("Wrong source offset for $target", source, escaper.getOffsetInHost(target, range))
             }
diff --git a/idea/tests/org/jetbrains/kotlin/search/KotlinReferencesSearchTest.kt b/idea/tests/org/jetbrains/kotlin/search/KotlinReferencesSearchTest.kt
index 5ba5e64aaec..f868c5baeac 100644
--- a/idea/tests/org/jetbrains/kotlin/search/KotlinReferencesSearchTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/search/KotlinReferencesSearchTest.kt
@@ -35,7 +35,7 @@ public class KotlinReferencesSearchTest(): AbstractSearcherTest() {
 
     public fun testPlus() {
         val refs = doTest<KtFunction>()
-        Assert.assertEquals(3, refs.size())
+        Assert.assertEquals(3, refs.size)
         Assert.assertEquals("+", refs[0].getCanonicalText())
         Assert.assertEquals("plus", refs[1].getCanonicalText())
         Assert.assertEquals("plus", refs[2].getCanonicalText())
@@ -43,7 +43,7 @@ public class KotlinReferencesSearchTest(): AbstractSearcherTest() {
 
     public fun testParam() {
         val refs = doTest<KtParameter>()
-        Assert.assertEquals(3, refs.size())
+        Assert.assertEquals(3, refs.size)
         Assert.assertEquals("n", refs[0].getCanonicalText())
         Assert.assertEquals("component1", refs[1].getCanonicalText())
         Assert.assertTrue(refs[2] is KtDestructuringDeclarationReference)