KT-5287 J2K: Convert class with private constructor and static functions to "object" instead of class with "class object"

#KT-5287 Fixed

j2k/src/org/jetbrains/kotlin/j2k/ClassBodyConverter.kt

@@ -49,14 +49,15 @@ enum class AccessorKind {
 
 class ClassBodyConverter(private val psiClass: PsiClass,
                          private val converter: Converter,
-                         private val isOpenClass: Boolean) {
+                         private val isOpenClass: Boolean,
+                         private val isObject: Boolean) {
     private val membersToRemove = HashSet<PsiMember>()
     private val fieldCorrections = HashMap<PsiField, FieldCorrectionInfo>()
 
     public fun convertBody(): ClassBody {
         processAccessorsToDrop()
 
-        val constructorConverter = if (psiClass.getName() != null)
+        val constructorConverter = if (psiClass.getName() != null && !isObject)
             ConstructorConverter(psiClass, converter, fieldCorrections)
         else
             null
@@ -65,9 +66,10 @@ class ClassBodyConverter(private val psiClass: PsiClass,
         for (element in psiClass.getChildren()) {
             if (element is PsiMember) {
                 if (element is PsiAnnotationMethod) continue // converted in convertAnnotationType()
+                if (isObject && element.isConstructor()) continue // no constructor in object
 
                 val converted = converter.convertMember(element, membersToRemove, constructorConverter)
-                if (converted != null/* && !converted.isEmpty()*/) {
+                if (converted != null) {
                     convertedMembers.put(element, converted)
                 }
             }
@@ -77,6 +79,13 @@ class ClassBodyConverter(private val psiClass: PsiClass,
             convertedMembers.remove(member)
         }
 
+        val lBrace = LBrace().assignPrototype(psiClass.getLBrace())
+        val rBrace = RBrace().assignPrototype(psiClass.getRBrace())
+
+        if (isObject) {
+            return ClassBody(null, emptyList(), convertedMembers.values().toList(), emptyList(), lBrace, rBrace)
+        }
+
         val useCompanionObject = shouldGenerateCompanionObject(convertedMembers)
 
         val members = ArrayList<Member>()
@@ -105,9 +114,6 @@ class ClassBodyConverter(private val psiClass: PsiClass,
             primaryConstructorSignature = null // no "()" after class name is needed in this case
         }
 
-        val lBrace = LBrace().assignPrototype(psiClass.getLBrace())
-        val rBrace = RBrace().assignPrototype(psiClass.getRBrace())
-
         return ClassBody(primaryConstructorSignature, constructorConverter?.baseClassParams ?: listOf(), members, companionObjectMembers, lBrace, rBrace)
     }
 

j2k/src/org/jetbrains/kotlin/j2k/CodeConverter.kt

@@ -153,7 +153,7 @@ class CodeConverter(
     }
 
     public fun convertAnonymousClassBody(anonymousClass: PsiAnonymousClass): AnonymousClassBody {
-        return AnonymousClassBody(ClassBodyConverter(anonymousClass, converter, false).convertBody(),
+        return AnonymousClassBody(ClassBodyConverter(anonymousClass, converter, isOpenClass = false, isObject = false).convertBody(),
                                   anonymousClass.getBaseClassType().resolve()?.isInterface() ?: false).assignPrototype(anonymousClass)
     }
 

j2k/src/org/jetbrains/kotlin/j2k/Converter.kt

@@ -16,20 +16,21 @@
 
 package org.jetbrains.kotlin.j2k
 
+import com.intellij.openapi.project.Project
 import com.intellij.psi.*
+import com.intellij.psi.CommonClassNames.*
+import com.intellij.psi.util.PsiMethodUtil
+import com.intellij.psi.util.PsiTreeUtil
 import org.jetbrains.kotlin.j2k.ast.*
 import org.jetbrains.kotlin.j2k.ast.Annotation
 import org.jetbrains.kotlin.j2k.ast.Class
 import org.jetbrains.kotlin.j2k.ast.Enum
-import java.util.*
-import com.intellij.psi.CommonClassNames.*
-import org.jetbrains.kotlin.types.expressions.OperatorConventions.*
-import com.intellij.openapi.project.Project
-import com.intellij.psi.util.PsiMethodUtil
-import com.intellij.psi.util.PsiTreeUtil
-import org.jetbrains.kotlin.j2k.usageProcessing.UsageProcessing
+import org.jetbrains.kotlin.j2k.ast.Object
 import org.jetbrains.kotlin.j2k.usageProcessing.FieldToPropertyProcessing
+import org.jetbrains.kotlin.j2k.usageProcessing.UsageProcessing
 import org.jetbrains.kotlin.j2k.usageProcessing.UsageProcessingExpressionConverter
+import org.jetbrains.kotlin.types.expressions.OperatorConventions.*
+import java.util.ArrayList
 
 class Converter private(
         private val elementToConvert: PsiElement,
@@ -150,42 +151,71 @@ class Converter private(
         val annotations = convertAnnotations(psiClass)
         var modifiers = convertModifiers(psiClass)
         val typeParameters = convertTypeParameterList(psiClass.getTypeParameterList())
-        val implementsTypes = convertToNotNullableTypes(psiClass.getImplementsListTypes())
         val extendsTypes = convertToNotNullableTypes(psiClass.getExtendsListTypes())
+        val implementsTypes = convertToNotNullableTypes(psiClass.getImplementsListTypes())
         val name = psiClass.declarationIdentifier()
 
         return when {
             psiClass.isInterface() -> {
-                var classBody = ClassBodyConverter(psiClass, this, false).convertBody()
+                val classBody = ClassBodyConverter(psiClass, this, isOpenClass = false, isObject = false).convertBody()
                 Trait(name, annotations, modifiers, typeParameters, extendsTypes, listOf(), implementsTypes, classBody)
             }
 
             psiClass.isEnum() -> {
-                var classBody = ClassBodyConverter(psiClass, this, false).convertBody()
+                val classBody = ClassBodyConverter(psiClass, this, isOpenClass = false, isObject = false).convertBody()
                 Enum(name, annotations, modifiers, typeParameters, listOf(), listOf(), implementsTypes, classBody)
             }
 
             else -> {
-                if (needOpenModifier(psiClass)) {
-                    modifiers = modifiers.with(Modifier.OPEN)
+                if (shouldConvertIntoObject(psiClass)) {
+                    val classBody = ClassBodyConverter(psiClass, this, isOpenClass = false, isObject = true).convertBody()
+                    Object(name, annotations, modifiers.without(Modifier.ABSTRACT), classBody)
                 }
+                else {
+                    if (psiClass.getContainingClass() != null && !psiClass.hasModifierProperty(PsiModifier.STATIC)) {
+                        modifiers = modifiers.with(Modifier.INNER)
+                    }
 
-                if (psiClass.getContainingClass() != null && !psiClass.hasModifierProperty(PsiModifier.STATIC)) {
-                    modifiers = modifiers.with(Modifier.INNER)
+                    val openModifier = if (psiClass.hasModifierProperty(PsiModifier.FINAL) || psiClass.hasModifierProperty(PsiModifier.ABSTRACT))
+                        false
+                    else
+                        settings.openByDefault || referenceSearcher.hasInheritors(psiClass)
+
+                    if (openModifier) {
+                        modifiers = modifiers.with(Modifier.OPEN)
+                    }
+
+                    val classBody = ClassBodyConverter(psiClass, this, modifiers.contains(Modifier.OPEN) || modifiers.contains(Modifier.ABSTRACT), isObject = false).convertBody()
+                    Class(name, annotations, modifiers, typeParameters, extendsTypes, classBody.baseClassParams, implementsTypes, classBody)
                 }
-
-                var classBody = ClassBodyConverter(psiClass, this, modifiers.contains(Modifier.OPEN)).convertBody()
-
-                Class(name, annotations, modifiers, typeParameters, extendsTypes, classBody.baseClassParams, implementsTypes, classBody)
             }
         }.assignPrototype(psiClass)
     }
 
-    private fun needOpenModifier(psiClass: PsiClass): Boolean {
-        return if (settings.openByDefault)
-            !psiClass.hasModifierProperty(PsiModifier.FINAL) && !psiClass.hasModifierProperty(PsiModifier.ABSTRACT)
-        else
-            referenceSearcher.hasInheritors(psiClass)
+    private fun shouldConvertIntoObject(psiClass: PsiClass): Boolean {
+        val methods = psiClass.getMethods()
+        val fields = psiClass.getFields()
+        val classes = psiClass.getInnerClasses()
+        if (methods.isEmpty() && fields.isEmpty()) return false
+        fun isStatic(member: PsiMember) = member.hasModifierProperty(PsiModifier.STATIC)
+        if (!methods.all { isStatic(it) || it.isConstructor() } || !fields.all(::isStatic) || !classes.all(::isStatic)) return false
+
+        val constructors = psiClass.getConstructors()
+        if (constructors.size() > 1) return false
+        val constructor = constructors.singleOrNull()
+        if (constructor != null) {
+            if (!constructor.hasModifierProperty(PsiModifier.PRIVATE)) return false
+            if (constructor.getParameterList().getParameters().isNotEmpty()) return false
+            if (constructor.getBody()?.getStatements()?.isNotEmpty() ?: false) return false
+            if (constructor.getModifierList().getAnnotations().isNotEmpty()) return false
+        }
+
+        if (psiClass.getExtendsListTypes().isNotEmpty() || psiClass.getImplementsListTypes().isNotEmpty()) return false
+        if (psiClass.getTypeParameters().isNotEmpty()) return false
+
+        if (referenceSearcher.hasInheritors(psiClass)) return false
+
+        return true
     }
 
     private fun convertAnnotationType(psiClass: PsiClass): Class {
@@ -215,7 +245,7 @@ class Converter private(
             null
 
         // to convert fields and nested types - they are not allowed in Kotlin but we convert them and let user refactor code
-        var classBody = ClassBodyConverter(psiClass, this, false).convertBody()
+        var classBody = ClassBodyConverter(psiClass, this, isOpenClass = false, isObject = false).convertBody()
         classBody = ClassBody(constructorSignature, classBody.baseClassParams, classBody.members, classBody.companionObjectMembers, classBody.lBrace, classBody.rBrace)
 
         val annotationAnnotation = Annotation(Identifier("annotation").assignNoPrototype(), listOf(), false, false).assignNoPrototype()

j2k/src/org/jetbrains/kotlin/j2k/ast/Class.kt

@@ -16,7 +16,8 @@
 
 package org.jetbrains.kotlin.j2k.ast
 
-import org.jetbrains.kotlin.j2k.*
+import org.jetbrains.kotlin.j2k.CodeBuilder
+import org.jetbrains.kotlin.j2k.append
 
 open class Class(
         val name: Identifier,
@@ -68,3 +69,14 @@ open class Class(
     protected open fun presentationModifiers(): Modifiers
             = if (modifiers.contains(Modifier.ABSTRACT)) modifiers.without(Modifier.OPEN) else modifiers
 }
+
+class Object(
+        name: Identifier,
+        annotations: Annotations,
+        modifiers: Modifiers,
+        body: ClassBody
+) : Class(name, annotations, modifiers, TypeParameterList.Empty, emptyList(), emptyList(), emptyList(), body) {
+
+    override val keyword: String
+        get() = "object"
+}

j2k/testData/fileOrElement/anonymousBlock/oneStaticAnonBlock.kt

@@ -1,9 +1,7 @@
-class Test {
-    companion object {
-        var str: String
+object Test {
+    var str: String
 
-        init {
-            str = "Ola"
-        }
+    init {
+        str = "Ola"
     }
 }

j2k/testData/fileOrElement/callChainExpression/libraryFieldCall.kt

@@ -1,8 +1,6 @@
 // ERROR: Property must be initialized or be abstract
-class Library {
-    companion object {
-        val ourOut: java.io.PrintStream
-    }
+object Library {
+    val ourOut: java.io.PrintStream
 }
 
 class User {

j2k/testData/fileOrElement/callChainExpression/libraryMethodCall.kt

@@ -1,11 +1,9 @@
-class Library {
-    companion object {
-        fun call() {
-        }
+object Library {
+    fun call() {
+    }
 
-        fun getString(): String {
-            return ""
-        }
+    fun getString(): String {
+        return ""
     }
 }
 

j2k/testData/fileOrElement/class/ClassShadowing.java

@@ -1,7 +1,10 @@
 package test;
 
+import java.lang.String;
+
 public class Short {
-	public static Short valueOf(String value) {return new Short();}
+        public Short(String s){}
+	public static Short valueOf(String value) {return new Short(value);}
 }
 
 class Test {

j2k/testData/fileOrElement/class/ClassShadowing.kt

@@ -1,19 +1,17 @@
 package test
 
-public class Short {
+public class Short(s: String) {
     companion object {
         public fun valueOf(value: String): Short {
-            return Short()
+            return Short(value)
         }
     }
 }
 
-class Test {
-    companion object {
-        public fun test() {
-            test.Short.valueOf("1")
-            test.Short.valueOf("1")
-            java.lang.Short.valueOf("1")
-        }
+object Test {
+    public fun test() {
+        test.Short.valueOf("1")
+        test.Short.valueOf("1")
+        java.lang.Short.valueOf("1")
     }
 }

j2k/testData/fileOrElement/class/notUtilityClass.java

@@ -0,0 +1,7 @@
+class Base {
+    public static final int CONSTANT = 10;
+}
+
+class Derived extends Base {
+    void foo(){}
+}

j2k/testData/fileOrElement/class/notUtilityClass.kt

@@ -0,0 +1,10 @@
+open class Base {
+    companion object {
+        public val CONSTANT: Int = 10
+    }
+}
+
+class Derived : Base() {
+    fun foo() {
+    }
+}

j2k/testData/fileOrElement/class/oneStaticMethod.kt

@@ -1,7 +1,5 @@
-class S {
-    companion object {
-        fun staticF(): Boolean {
-            return true
-        }
+object S {
+    fun staticF(): Boolean {
+        return true
     }
 }

j2k/testData/fileOrElement/class/twoStaticMethod.kt

@@ -1,11 +1,9 @@
-class S {
-    companion object {
-        fun sB(): Boolean {
-            return true
-        }
+object S {
+    fun sB(): Boolean {
+        return true
+    }
 
-        fun sI(): Int {
-            return 1
-        }
+    fun sI(): Int {
+        return 1
     }
 }

j2k/testData/fileOrElement/class/utilityClass1.java

@@ -0,0 +1,6 @@
+class Util {
+    public static void util1() {}
+    public static void util2() {}
+
+    public static final int CONSTANT = 10;
+}

j2k/testData/fileOrElement/class/utilityClass1.kt

@@ -0,0 +1,9 @@
+object Util {
+    public fun util1() {
+    }
+
+    public fun util2() {
+    }
+
+    public val CONSTANT: Int = 10
+}

j2k/testData/fileOrElement/class/utilityClass2.java

@@ -0,0 +1,8 @@
+class Util {
+    private Util(){}
+
+    public static void util1() {}
+    public static void util2() {}
+
+    public static final int CONSTANT = 10;
+}

j2k/testData/fileOrElement/class/utilityClass2.kt

@@ -0,0 +1,10 @@
+object Util {
+
+    public fun util1() {
+    }
+
+    public fun util2() {
+    }
+
+    public val CONSTANT: Int = 10
+}

j2k/testData/fileOrElement/class/utilityClass3.java

@@ -0,0 +1,6 @@
+abstract class Util {
+    public static void util1() {}
+    public static void util2() {}
+
+    public static final int CONSTANT = 10;
+}

j2k/testData/fileOrElement/class/utilityClass3.kt

@@ -0,0 +1,9 @@
+object Util {
+    public fun util1() {
+    }
+
+    public fun util2() {
+    }
+
+    public val CONSTANT: Int = 10
+}

j2k/testData/fileOrElement/classExpression/primitivesAndArrays.kt

@@ -1,13 +1,11 @@
-public class A {
-    companion object {
-        public fun main(args: Array<String>) {
-            System.out.println(Void.TYPE)
-            System.out.println(Integer.TYPE)
-            System.out.println(java.lang.Double.TYPE)
-            System.out.println(javaClass<IntArray>())
-            System.out.println(javaClass<Array<Any>>())
-            System.out.println(javaClass<Array<Array<Any>>>())
-        }
+public object A {
+    public fun main(args: Array<String>) {
+        System.out.println(Void.TYPE)
+        System.out.println(Integer.TYPE)
+        System.out.println(java.lang.Double.TYPE)
+        System.out.println(javaClass<IntArray>())
+        System.out.println(javaClass<Array<Any>>())
+        System.out.println(javaClass<Array<Array<Any>>>())
     }
 }
 

j2k/testData/fileOrElement/constructors/allCallsPrimary.kt

@@ -2,12 +2,10 @@ package pack
 
 class C(arg1: Int, arg2: Int = 0, arg3: Int = 0)
 
-public class User {
-    companion object {
-        public fun main() {
-            val c1 = C(100, 100, 100)
-            val c2 = C(100, 100)
-            val c3 = C(100)
-        }
+public object User {
+    public fun main() {
+        val c1 = C(100, 100, 100)
+        val c2 = C(100, 100)
+        val c3 = C(100)
     }
 }

j2k/testData/fileOrElement/constructors/allCallsPrimary2.kt

@@ -18,12 +18,10 @@ class C(val myArg1: Int) {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val c1 = C(100, 100, 100)
-            val c2 = C(100, 100)
-            val c3 = C(100)
-        }
+public object User {
+    public fun main() {
+        val c1 = C(100, 100, 100)
+        val c2 = C(100, 100)
+        val c3 = C(100)
     }
 }

j2k/testData/fileOrElement/constructors/chain.kt

@@ -9,12 +9,10 @@ class C(arg1: Int, arg2: Int, arg3: Int) {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val c1 = C(1, 2, 3)
-            val c2 = C(5, 6)
-            val c3 = C(7)
-        }
+public object User {
+    public fun main() {
+        val c1 = C(1, 2, 3)
+        val c2 = C(5, 6)
+        val c3 = C(7)
     }
 }

j2k/testData/fileOrElement/constructors/customerBuilder.kt

@@ -33,12 +33,10 @@ class CustomerBuilder {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val customer = CustomerBuilder().WithFirstName("Homer").WithLastName("Simpson").Build()
-            System.out.println(customer.firstName)
-            System.out.println(customer.lastName)
-        }
+public object User {
+    public fun main() {
+        val customer = CustomerBuilder().WithFirstName("Homer").WithLastName("Simpson").Build()
+        System.out.println(customer.firstName)
+        System.out.println(customer.lastName)
     }
 }

j2k/testData/fileOrElement/constructors/genericIdentifier.kt

@@ -20,12 +20,10 @@ public class Identifier<T> {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val i1 = Identifier("name", false, true)
-            val i2 = Identifier("name", false)
-            val i3 = Identifier("name")
-        }
+public object User {
+    public fun main() {
+        val i1 = Identifier("name", false, true)
+        val i2 = Identifier("name", false)
+        val i3 = Identifier("name")
     }
 }

j2k/testData/fileOrElement/constructors/identifier.kt

@@ -20,12 +20,10 @@ public class Identifier {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val i1 = Identifier("name", false, true)
-            val i2 = Identifier("name", false)
-            val i3 = Identifier("name")
-        }
+public object User {
+    public fun main() {
+        val i1 = Identifier("name", false, true)
+        val i2 = Identifier("name", false)
+        val i3 = Identifier("name")
     }
 }

j2k/testData/fileOrElement/constructors/noPrimary.kt

@@ -11,12 +11,10 @@ class C {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val c1 = C(1, 2, 3)
-            val c2 = C(5, 6)
-            val c3 = C(7)
-        }
+public object User {
+    public fun main() {
+        val c1 = C(1, 2, 3)
+        val c2 = C(5, 6)
+        val c3 = C(7)
     }
 }

j2k/testData/fileOrElement/constructors/parameterModification.kt

@@ -17,12 +17,10 @@ class C(arg1: Int, arg2: Int = 0, arg3: Int = 0) {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val c1 = C(100, 100, 100)
-            val c2 = C(100, 100)
-            val c3 = C(100)
-        }
+public object User {
+    public fun main() {
+        val c1 = C(100, 100, 100)
+        val c2 = C(100, 100)
+        val c3 = C(100)
     }
 }

j2k/testData/fileOrElement/constructors/secondaryConstructorsInNestedClass.kt

@@ -1,4 +1,4 @@
-class Outer {
+object Outer {
     private class Nested1() {
 
         public constructor(a: Int) : this() {
@@ -48,13 +48,10 @@ class Outer {
         }
     }
 
-    companion object {
-
-        fun foo() {
-            val nested1 = Nested1(1)
-            val nested2 = Nested2(2)
-            val nested3 = Nested3(3)
-            val nested4 = Nested4(4)
-        }
+    fun foo() {
+        val nested1 = Nested1(1)
+        val nested2 = Nested2(2)
+        val nested3 = Nested3(3)
+        val nested4 = Nested4(4)
     }
 }

j2k/testData/fileOrElement/constructors/withManyDefaultParams.kt

@@ -24,10 +24,8 @@ public class Test {
     }
 }
 
-public class User {
-    companion object {
-        public fun main() {
-            val t = Test("name")
-        }
+public object User {
+    public fun main() {
+        val t = Test("name")
     }
 }

j2k/testData/fileOrElement/for/withContinue1.kt

@@ -1,16 +1,14 @@
-public class TestClass {
-    companion object {
-        public fun main(args: Array<String>) {
-            var i = 0
-            while (i < 10) {
-                if (i == 4 || i == 8) {
-                    i++
-                    ++i
-                    continue
-                }
-                System.err.println(i)
+public object TestClass {
+    public fun main(args: Array<String>) {
+        var i = 0
+        while (i < 10) {
+            if (i == 4 || i == 8) {
+                i++
                 ++i
+                continue
             }
+            System.err.println(i)
+            ++i
         }
     }
 }

j2k/testData/fileOrElement/for/withContinue2.kt

@@ -1,19 +1,17 @@
-public class TestClass {
-    companion object {
-        public fun main(args: Array<String>) {
-            var i = 0
-            var j = 1
-            while (i < 10) {
-                if (i == 4 || i == 8) {
-                    i++
-                    ++i
-                    j *= 2
-                    continue
-                }
-                System.err.println(j)
+public object TestClass {
+    public fun main(args: Array<String>) {
+        var i = 0
+        var j = 1
+        while (i < 10) {
+            if (i == 4 || i == 8) {
+                i++
                 ++i
                 j *= 2
+                continue
             }
+            System.err.println(j)
+            ++i
+            j *= 2
         }
     }
 }

j2k/testData/fileOrElement/for/withContinue3.kt

@@ -1,15 +1,13 @@
-public class TestClass {
-    companion object {
-        public fun main(args: Array<String>) {
-            var i = 1
-            while (i < 1000) {
-                if (i == 4 || i == 8) {
-                    i *= 2
-                    continue
-                }
-                System.err.println(i)
+public object TestClass {
+    public fun main(args: Array<String>) {
+        var i = 1
+        while (i < 1000) {
+            if (i == 4 || i == 8) {
                 i *= 2
+                continue
             }
+            System.err.println(i)
+            i *= 2
         }
     }
 }

j2k/testData/fileOrElement/for/withContinueAndLabels.kt

@@ -1,28 +1,26 @@
 // ERROR: The label '@OuterLoop1' does not denote a loop
-public class TestClass {
-    companion object {
-        public fun main(args: Array<String>) {
-            var i = 1
-            @OuterLoop1 @OuterLoop2 while (i < 1000) {
-                var j = 1
-                @InnerLoop while (j < 100) {
-                    if (j == 3) {
-                        j *= 3
-                        continue@InnerLoop
-                    }
-                    if (i == j) {
-                        i *= 2
-                        continue@OuterLoop1
-                    }
-                    System.err.println(j)
-                    if (j == 9) {
-                        j *= 3
-                        continue
-                    }
+public object TestClass {
+    public fun main(args: Array<String>) {
+        var i = 1
+        @OuterLoop1 @OuterLoop2 while (i < 1000) {
+            var j = 1
+            @InnerLoop while (j < 100) {
+                if (j == 3) {
                     j *= 3
+                    continue@InnerLoop
                 }
-                i *= 2
+                if (i == j) {
+                    i *= 2
+                    continue@OuterLoop1
+                }
+                System.err.println(j)
+                if (j == 9) {
+                    j *= 3
+                    continue
+                }
+                j *= 3
             }
+            i *= 2
         }
     }
 }

j2k/testData/fileOrElement/formatting/staticMembersWithComments.kt

@@ -1,28 +1,26 @@
-class F {
-    companion object {
+object F {
 
-        //c1
+    //c1
 
-        /*c2*/
+    /*c2*/
 
-        fun f1() {
-        }
+    fun f1() {
+    }
 
 
-        //c3
+    //c3
 
 
 
 
-        //c4
+    //c4
 
-        fun f2() {
-        }
+    fun f2() {
+    }
 
-        var i: Int? = 0
+    var i: Int? = 0
 
-        fun f3() {
-        }
+    fun f3() {
     }
 
     //c5

j2k/testData/fileOrElement/function/main.kt

@@ -1,4 +1,2 @@
-companion object {
-    public fun main(args: Array<String>) {
-    }
+public fun main(args: Array<String>) {
 }

j2k/testData/fileOrElement/function/main2.kt

@@ -1,7 +1,5 @@
-public class A {
-    companion object {
-        public fun main(args: Array<String>) {
-        }
+public object A {
+    public fun main(args: Array<String>) {
     }
 }
 

j2k/testData/fileOrElement/function/mainAndNullabilitySetting.kt

@@ -1,8 +1,6 @@
 // !forceNotNullTypes: false
-public class A {
-    companion object {
-        public fun main(args: Array<String>) {
-        }
+public object A {
+    public fun main(args: Array<String>) {
     }
 }
 

j2k/testData/fileOrElement/issues/arrayLength.kt

@@ -1,7 +1,5 @@
-class Test {
-    companion object {
-        public fun foo(args: Array<String>): Int {
-            return args.size()
-        }
+object Test {
+    public fun foo(args: Array<String>): Int {
+        return args.size()
     }
 }

j2k/testData/fileOrElement/issues/doNotQualifyStatic.kt

@@ -1,12 +1,9 @@
-class Outer {
+object Outer {
+    public var o: Any? = Object()
 
     public class Nested {
         public fun foo() {
             o = null
         }
     }
-
-    companion object {
-        public var o: Any? = Object()
-    }
-}
+}

j2k/testData/fileOrElement/issues/kt-1074.kt

@@ -1,14 +1,12 @@
 package demo
 
-class Test {
-    companion object {
-        fun subListRangeCheck(fromIndex: Int, toIndex: Int, size: Int) {
-            if (fromIndex < 0)
-                throw IndexOutOfBoundsException("fromIndex = " + fromIndex)
-            if (toIndex > size)
-                throw IndexOutOfBoundsException("toIndex = " + toIndex)
-            if (fromIndex > toIndex)
-                throw IllegalArgumentException("fromIndex(" + fromIndex + ") > toIndex(" + toIndex + ")")
-        }
+object Test {
+    fun subListRangeCheck(fromIndex: Int, toIndex: Int, size: Int) {
+        if (fromIndex < 0)
+            throw IndexOutOfBoundsException("fromIndex = " + fromIndex)
+        if (toIndex > size)
+            throw IndexOutOfBoundsException("toIndex = " + toIndex)
+        if (fromIndex > toIndex)
+            throw IllegalArgumentException("fromIndex(" + fromIndex + ") > toIndex(" + toIndex + ")")
     }
 }

j2k/testData/fileOrElement/issues/kt-638.kt

@@ -20,13 +20,11 @@ public class Identifier<T> {
     }
 }
 
-public class User {
-    companion object {
-        public fun main(args: Array<String>) {
-            val i1 = Identifier("name", false, true)
-            val i2 = Identifier("name", false)
-            val i3 = Identifier("name")
-        }
+public object User {
+    public fun main(args: Array<String>) {
+        val i1 = Identifier("name", false, true)
+        val i2 = Identifier("name", false)
+        val i3 = Identifier("name")
     }
 }
 

j2k/testData/fileOrElement/issues/kt-807.kt

@@ -4,23 +4,21 @@
 // ERROR: Unresolved reference: close
 import java.io.*
 
-class FileRead {
-    companion object {
-        public fun main(args: Array<String>) {
-            try {
-                val fstream = FileInputStream()
-                val `in` = DataInputStream(fstream)
-                val br = BufferedReader(InputStreamReader(`in`))
-                val strLine: String
-                while ((strLine = br.readLine()) != null) {
-                    System.out.println(strLine)
-                }
-                `in`.close()
-            } catch (e: Exception) {
-                System.err.println("Error: " + e.getMessage())
+object FileRead {
+    public fun main(args: Array<String>) {
+        try {
+            val fstream = FileInputStream()
+            val `in` = DataInputStream(fstream)
+            val br = BufferedReader(InputStreamReader(`in`))
+            val strLine: String
+            while ((strLine = br.readLine()) != null) {
+                System.out.println(strLine)
             }
-
+            `in`.close()
+        } catch (e: Exception) {
+            System.err.println("Error: " + e.getMessage())
         }
+
     }
 }
 

j2k/testData/fileOrElement/issues/kt-809-string.kt

@@ -4,10 +4,8 @@ class Container {
     var myString = "1"
 }
 
-class One {
-    companion object {
-        var myContainer = Container()
-    }
+object One {
+    var myContainer = Container()
 }
 
 class StringContainer(s: String)

j2k/testData/fileOrElement/issues/kt-809.kt

@@ -4,10 +4,8 @@ class Container {
     var myInt = 1
 }
 
-class One {
-    companion object {
-        var myContainer = Container()
-    }
+object One {
+    var myContainer = Container()
 }
 
 class IntContainer(i: Int)

j2k/testData/fileOrElement/issues/kt-820-field.kt

@@ -4,10 +4,8 @@ class Container {
     var myInt = 1
 }
 
-class One {
-    companion object {
-        var myContainer = Container()
-    }
+object One {
+    var myContainer = Container()
 }
 
 class Test {

j2k/testData/fileOrElement/issues/kt-820-string.kt

@@ -1,8 +1,6 @@
-class Test {
-    companion object {
-        public fun toFileSystemSafeName(name: String): String {
-            val size = name.length()
-            return name
-        }
+object Test {
+    public fun toFileSystemSafeName(name: String): String {
+        val size = name.length()
+        return name
     }
 }

j2k/testData/fileOrElement/issues/kt-820.kt

@@ -4,10 +4,8 @@ class Container {
     var myInt = 1
 }
 
-class One {
-    companion object {
-        var myContainer = Container()
-    }
+object One {
+    var myContainer = Container()
 }
 
 class Test {

j2k/testData/fileOrElement/issues/kt-824-isDir.kt

@@ -5,17 +5,15 @@ import java.io.File
 /**
  * User: ignatov
  */
-public class Test {
-    companion object {
-        public fun isDir(parent: File?): Boolean {
-            if (parent == null || !parent.exists()) {
-                return false
-            }
-            val result = true
-            if (parent.isDirectory()) {
-                return true
-            } else
-                return false
+public object Test {
+    public fun isDir(parent: File?): Boolean {
+        if (parent == null || !parent.exists()) {
+            return false
         }
+        val result = true
+        if (parent.isDirectory()) {
+            return true
+        } else
+            return false
     }
 }

j2k/testData/fileOrElement/issues/kt-824.kt

@@ -4,10 +4,8 @@ class Container {
     var myBoolean = true
 }
 
-class One {
-    companion object {
-        var myContainer = Container()
-    }
+object One {
+    var myContainer = Container()
 }
 
 class Test {

j2k/testData/fileOrElement/issues/kt-871.kt

@@ -1,10 +1,8 @@
 package demo
 
-class Program {
-    companion object {
-        public fun main(args: Array<String>) {
-            System.out.println("Halo!")
-        }
+object Program {
+    public fun main(args: Array<String>) {
+        System.out.println("Halo!")
     }
 }
 

j2k/testData/fileOrElement/issues/kt-879.kt

@@ -1,13 +1,11 @@
-class Test {
-    companion object {
-        public fun getInt(i: Int): Int {
-            when (i) {
-                0 -> return 0
-                1 -> return 1
-                2 -> return 2
-                3 -> return 3
-                else -> return -1
-            }
+object Test {
+    public fun getInt(i: Int): Int {
+        when (i) {
+            0 -> return 0
+            1 -> return 1
+            2 -> return 2
+            3 -> return 3
+            else -> return -1
         }
     }
 }

j2k/testData/fileOrElement/methodCallExpression/vararg1.kt

@@ -1,11 +1,9 @@
 import java.lang.reflect.Constructor
 
-class X {
-    companion object {
-        throws(javaClass<Exception>())
-        fun <T> foo(constructor: Constructor<T>, args1: Array<Any>, args2: Array<Any>) {
-            constructor.newInstance(*args1)
-            constructor.newInstance(args1, args2)
-        }
+object X {
+    throws(javaClass<Exception>())
+    fun <T> foo(constructor: Constructor<T>, args1: Array<Any>, args2: Array<Any>) {
+        constructor.newInstance(*args1)
+        constructor.newInstance(args1, args2)
     }
 }

j2k/testData/fileOrElement/switch/comlicatedFallDown.kt

@@ -1,86 +1,84 @@
 package demo
 
-public class SwitchDemo {
-    companion object {
-        public fun print(o: Any) {
-            System.out.println(o)
-        }
+public object SwitchDemo {
+    public fun print(o: Any) {
+        System.out.println(o)
+    }
 
-        public fun test(i: Int) {
-            var monthString = "<empty>"
-            when (i) {
-                1 -> {
-                    print(1)
-                    print(2)
-                    print(3)
-                    print(4)
-                    print(5)
-                }
-                2 -> {
-                    print(2)
-                    print(3)
-                    print(4)
-                    print(5)
-                }
-                3 -> {
-                    print(3)
-                    print(4)
-                    print(5)
-                }
-                4 -> {
-                    print(4)
-                    print(5)
-                }
-                5 -> print(5)
-                6 -> {
-                    print(6)
-                    print(7)
-                    print(8)
-                    print(9)
-                    print(10)
-                    print(11)
-                    monthString = "December"
-                }
-                7 -> {
-                    print(7)
-                    print(8)
-                    print(9)
-                    print(10)
-                    print(11)
-                    monthString = "December"
-                }
-                8 -> {
-                    print(8)
-                    print(9)
-                    print(10)
-                    print(11)
-                    monthString = "December"
-                }
-                9 -> {
-                    print(9)
-                    print(10)
-                    print(11)
-                    monthString = "December"
-                }
-                10 -> {
-                    print(10)
-                    print(11)
-                    monthString = "December"
-                }
-                11 -> {
-                    print(11)
-                    monthString = "December"
-                }
-                12 -> monthString = "December"
-                else -> monthString = "Invalid month"
+    public fun test(i: Int) {
+        var monthString = "<empty>"
+        when (i) {
+            1 -> {
+                print(1)
+                print(2)
+                print(3)
+                print(4)
+                print(5)
             }
-            System.out.println(monthString)
+            2 -> {
+                print(2)
+                print(3)
+                print(4)
+                print(5)
+            }
+            3 -> {
+                print(3)
+                print(4)
+                print(5)
+            }
+            4 -> {
+                print(4)
+                print(5)
+            }
+            5 -> print(5)
+            6 -> {
+                print(6)
+                print(7)
+                print(8)
+                print(9)
+                print(10)
+                print(11)
+                monthString = "December"
+            }
+            7 -> {
+                print(7)
+                print(8)
+                print(9)
+                print(10)
+                print(11)
+                monthString = "December"
+            }
+            8 -> {
+                print(8)
+                print(9)
+                print(10)
+                print(11)
+                monthString = "December"
+            }
+            9 -> {
+                print(9)
+                print(10)
+                print(11)
+                monthString = "December"
+            }
+            10 -> {
+                print(10)
+                print(11)
+                monthString = "December"
+            }
+            11 -> {
+                print(11)
+                monthString = "December"
+            }
+            12 -> monthString = "December"
+            else -> monthString = "Invalid month"
         }
+        System.out.println(monthString)
+    }
 
-        public fun main(args: Array<String>) {
-            for (i in 1..12)
-                test(i)
-        }
+    public fun main(args: Array<String>) {
+        for (i in 1..12)
+            test(i)
     }
 }
 

j2k/testData/fileOrElement/switch/emptySwitch.kt

@@ -1,14 +1,12 @@
-public class NonDefault {
-    companion object {
-        public fun main(args: Array<String>) {
+public object NonDefault {
+    public fun main(args: Array<String>) {
 
-            val value = 3
-            val valueString = ""
-            when (value) {
+        val value = 3
+        val valueString = ""
+        when (value) {
 
-            }
-            System.out.println(valueString)
         }
+        System.out.println(valueString)
     }
 }
 

j2k/testData/fileOrElement/switch/fallDown.kt

@@ -1,16 +1,14 @@
 package switch_demo
 
-public class SwitchDemo {
-    companion object {
-        public fun main(args: Array<String>) {
-            val month = 8
-            val monthString: String
-            when (month) {
-                1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 -> monthString = "December"
-                else -> monthString = "Invalid month"
-            }
-            System.out.println(monthString)
+public object SwitchDemo {
+    public fun main(args: Array<String>) {
+        val month = 8
+        val monthString: String
+        when (month) {
+            1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 -> monthString = "December"
+            else -> monthString = "Invalid month"
         }
+        System.out.println(monthString)
     }
 }
 

j2k/testData/fileOrElement/switch/fallDownWithBlocks.kt

@@ -1,23 +1,21 @@
-public class C {
-    companion object {
-        public fun main(args: Array<String>) {
-            when (args.size()) {
-                1 -> {
-                    run {
-                        val a = 1
-                        System.out.print("1")
-                    }
-                    run {
-                        val a = 2
-                        System.out.print("2")
-                    }
+public object C {
+    public fun main(args: Array<String>) {
+        when (args.size()) {
+            1 -> {
+                run {
+                    val a = 1
+                    System.out.print("1")
                 }
-
-                2 -> {
+                run {
                     val a = 2
                     System.out.print("2")
                 }
             }
+
+            2 -> {
+                val a = 2
+                System.out.print("2")
+            }
         }
     }
 }

j2k/testData/fileOrElement/switch/kt-539.kt

@@ -1,28 +1,26 @@
 package switch_demo
 
-public class SwitchDemo {
-    companion object {
-        public fun main(args: Array<String>) {
+public object SwitchDemo {
+    public fun main(args: Array<String>) {
 
-            val month = 8
-            val monthString: String
-            when (month) {
-                1 -> monthString = "January"
-                2 -> monthString = "February"
-                3 -> monthString = "March"
-                4 -> monthString = "April"
-                5 -> monthString = "May"
-                6 -> monthString = "June"
-                7 -> monthString = "July"
-                8 -> monthString = "August"
-                9 -> monthString = "September"
-                10 -> monthString = "October"
-                11 -> monthString = "November"
-                12 -> monthString = "December"
-                else -> monthString = "Invalid month"
-            }
-            System.out.println(monthString)
+        val month = 8
+        val monthString: String
+        when (month) {
+            1 -> monthString = "January"
+            2 -> monthString = "February"
+            3 -> monthString = "March"
+            4 -> monthString = "April"
+            5 -> monthString = "May"
+            6 -> monthString = "June"
+            7 -> monthString = "July"
+            8 -> monthString = "August"
+            9 -> monthString = "September"
+            10 -> monthString = "October"
+            11 -> monthString = "November"
+            12 -> monthString = "December"
+            else -> monthString = "Invalid month"
         }
+        System.out.println(monthString)
     }
 }
 

j2k/testData/fileOrElement/switch/nondefault.kt

@@ -1,16 +1,14 @@
-public class NonDefault {
-    companion object {
-        public fun main(args: Array<String>) {
+public object NonDefault {
+    public fun main(args: Array<String>) {
 
-            val value = 3
-            var valueString = ""
-            when (value) {
-                1 -> valueString = "ONE"
-                2 -> valueString = "TWO"
-                3 -> valueString = "THREE"
-            }
-            System.out.println(valueString)
+        val value = 3
+        var valueString = ""
+        when (value) {
+            1 -> valueString = "ONE"
+            2 -> valueString = "TWO"
+            3 -> valueString = "THREE"
         }
+        System.out.println(valueString)
     }
 }
 

j2k/testData/fileOrElement/typeParameters/rawTypeCast.kt

@@ -1,11 +1,9 @@
 // ERROR: Type inference failed. Expected type mismatch: found: java.util.HashMap<kotlin.Any!, kotlin.Any!> required: kotlin.Map<kotlin.String, kotlin.String>
 import java.util.*
 
-class A {
-    companion object {
-        public fun foo(): Map<String, String> {
-            val props = Properties()
-            return HashMap(props as Map<Any, Any>)
-        }
+object A {
+    public fun foo(): Map<String, String> {
+        val props = Properties()
+        return HashMap(props as Map<Any, Any>)
     }
 }

j2k/tests/org/jetbrains/kotlin/j2k/AbstractJavaToKotlinConverterSingleFileTest.kt

@@ -119,7 +119,7 @@ public abstract class AbstractJavaToKotlinConverterSingleFileTest : AbstractJava
     }
 
     private fun methodToKotlin(text: String, settings: ConverterSettings, project: Project): String {
-        val result = fileToKotlin("final class C {" + text + "}", settings, project).replaceAll("class C \\{", "")
+        val result = fileToKotlin("final class C {" + text + "}", settings, project).replaceAll("class C \\{", "").replaceAll("object C \\{", "")
         return result.substring(0, (result.lastIndexOf("}"))).trim()
     }
 

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterForWebDemoTestGenerated.java

@@ -886,6 +886,12 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             doTest(fileName);
         }
 
+        @TestMetadata("notUtilityClass.java")
+        public void testNotUtilityClass() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/notUtilityClass.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("oneStaticFieldOneNonStatic.java")
         public void testOneStaticFieldOneNonStatic() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/oneStaticFieldOneNonStatic.java");
@@ -939,6 +945,24 @@ public class JavaToKotlinConverterForWebDemoTestGenerated extends AbstractJavaTo
             String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/twoStaticMethod.java");
             doTest(fileName);
         }
+
+        @TestMetadata("utilityClass1.java")
+        public void testUtilityClass1() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/utilityClass1.java");
+            doTest(fileName);
+        }
+
+        @TestMetadata("utilityClass2.java")
+        public void testUtilityClass2() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/utilityClass2.java");
+            doTest(fileName);
+        }
+
+        @TestMetadata("utilityClass3.java")
+        public void testUtilityClass3() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/utilityClass3.java");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("j2k/testData/fileOrElement/classExpression")

j2k/tests/org/jetbrains/kotlin/j2k/JavaToKotlinConverterSingleFileTestGenerated.java

@@ -886,6 +886,12 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             doTest(fileName);
         }
 
+        @TestMetadata("notUtilityClass.java")
+        public void testNotUtilityClass() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/notUtilityClass.java");
+            doTest(fileName);
+        }
+
         @TestMetadata("oneStaticFieldOneNonStatic.java")
         public void testOneStaticFieldOneNonStatic() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/oneStaticFieldOneNonStatic.java");
@@ -939,6 +945,24 @@ public class JavaToKotlinConverterSingleFileTestGenerated extends AbstractJavaTo
             String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/twoStaticMethod.java");
             doTest(fileName);
         }
+
+        @TestMetadata("utilityClass1.java")
+        public void testUtilityClass1() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/utilityClass1.java");
+            doTest(fileName);
+        }
+
+        @TestMetadata("utilityClass2.java")
+        public void testUtilityClass2() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/utilityClass2.java");
+            doTest(fileName);
+        }
+
+        @TestMetadata("utilityClass3.java")
+        public void testUtilityClass3() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("j2k/testData/fileOrElement/class/utilityClass3.java");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("j2k/testData/fileOrElement/classExpression")