diff --git a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PreliminaryLoopVisitor.java b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PreliminaryLoopVisitor.java
deleted file mode 100644
index 81112e97189..00000000000
--- a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PreliminaryLoopVisitor.java
+++ /dev/null
@@ -1,59 +0,0 @@
-/*
- * Copyright 2010-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.kotlin.types.expressions;
-
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.kotlin.descriptors.impl.LocalVariableDescriptor;
-import org.jetbrains.kotlin.psi.*;
-import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowInfo;
-import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValue;
-import org.jetbrains.kotlin.resolve.calls.smartcasts.Nullability;
-
-import java.util.*;
-
-/**
- * The purpose of this class is to find all variable assignments
- * <b>before</b> loop analysis
- */
-class PreliminaryLoopVisitor extends AssignedVariablesSearcher {
-
-    @NotNull
-    static public PreliminaryLoopVisitor visitLoop(@NotNull JetLoopExpression loopExpression) {
-        PreliminaryLoopVisitor visitor = new PreliminaryLoopVisitor();
-        loopExpression.accept(visitor, null);
-        return visitor;
-    }
-
-    @NotNull
-    public DataFlowInfo clearDataFlowInfoForAssignedLocalVariables(@NotNull DataFlowInfo dataFlowInfo) {
-        Map<DataFlowValue, Nullability> nullabilityMap = dataFlowInfo.getCompleteNullabilityInfo();
-        Set<DataFlowValue> valueSetToClear = new LinkedHashSet<DataFlowValue>();
-        for (DataFlowValue value: nullabilityMap.keySet()) {
-            // Only predictable variables are under interest here
-            if (value.getKind() == DataFlowValue.Kind.PREDICTABLE_VARIABLE && value.getId() instanceof LocalVariableDescriptor) {
-                LocalVariableDescriptor descriptor = (LocalVariableDescriptor)value.getId();
-                if (getAssignedNames().contains(descriptor.getName())) {
-                    valueSetToClear.add(value);
-                }
-            }
-        }
-        for (DataFlowValue valueToClear: valueSetToClear) {
-            dataFlowInfo = dataFlowInfo.clearValueInfo(valueToClear);
-        }
-        return dataFlowInfo;
-    }
-}
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PreliminaryLoopVisitor.kt b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PreliminaryLoopVisitor.kt
new file mode 100644
index 00000000000..14859e34bbf
--- /dev/null
+++ b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/PreliminaryLoopVisitor.kt
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.types.expressions
+
+import org.jetbrains.kotlin.descriptors.impl.LocalVariableDescriptor
+import org.jetbrains.kotlin.psi.JetLoopExpression
+import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowInfo
+import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValue
+import java.util.*
+
+/**
+ * The purpose of this class is to find all variable assignments
+ * **before** loop analysis
+ */
+class PreliminaryLoopVisitor private constructor() : AssignedVariablesSearcher() {
+
+    fun clearDataFlowInfoForAssignedLocalVariables(dataFlowInfo: DataFlowInfo): DataFlowInfo {
+        var resultFlowInfo = dataFlowInfo
+        val nullabilityMap = resultFlowInfo.completeNullabilityInfo
+        val valueSetToClear = LinkedHashSet<DataFlowValue>()
+        for (value in nullabilityMap.keySet()) {
+            // Only predictable variables are under interest here
+            val id = value.id
+            if (value.kind == DataFlowValue.Kind.PREDICTABLE_VARIABLE && id is LocalVariableDescriptor) {
+                if (assignedNames.contains(id.name)) {
+                    valueSetToClear.add(value)
+                }
+            }
+        }
+        for (valueToClear in valueSetToClear) {
+            resultFlowInfo = resultFlowInfo.clearValueInfo(valueToClear)
+        }
+        return resultFlowInfo
+    }
+
+    companion object {
+
+        @JvmStatic
+        fun visitLoop(loopExpression: JetLoopExpression): PreliminaryLoopVisitor {
+            val visitor = PreliminaryLoopVisitor()
+            loopExpression.accept(visitor, null)
+            return visitor
+        }
+    }
+}