1 files changed, 17 insertions, 5 deletions
diff --git a/java/java-impl/src/com/intellij/codeInsight/completion/LambdaCompletionProvider.java b/java/java-impl/src/com/intellij/codeInsight/completion/LambdaCompletionProvider.java
index f169ccd8aa56..4fd7df6c7e2e 100644
--- a/java/java-impl/src/com/intellij/codeInsight/completion/LambdaCompletionProvider.java
+++ b/java/java-impl/src/com/intellij/codeInsight/completion/LambdaCompletionProvider.java
@@ -25,6 +25,7 @@ import com.intellij.openapi.editor.EditorModificationUtil;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.*;
+import com.intellij.psi.codeStyle.CodeStyleManager;
 import com.intellij.psi.codeStyle.JavaCodeStyleManager;
 import com.intellij.psi.impl.source.resolve.graphInference.FunctionalInterfaceParameterizationUtil;
 import com.intellij.psi.util.PsiUtil;
@@ -52,18 +53,25 @@ public class LambdaCompletionProvider extends CompletionProvider<CompletionParam
           final Project project = method.getProject();
           final PsiElement originalPosition = parameters.getOriginalPosition();
           final JVMElementFactory jvmElementFactory = originalPosition != null ? JVMElementFactories.getFactory(originalPosition.getLanguage(), project) : null;
+          final JavaCodeStyleManager javaCodeStyleManager = JavaCodeStyleManager.getInstance(project);
           if (jvmElementFactory != null) {
             final PsiSubstitutor substitutor = LambdaUtil.getSubstitutor(method, PsiUtil.resolveGenericsClassInType(functionalInterfaceType));
-            final JavaCodeStyleManager codeStyleManager = JavaCodeStyleManager.getInstance(project);
-            params = GenerateMembersUtil.overriddenParameters(params, jvmElementFactory, codeStyleManager, substitutor, originalPosition);
+            params = GenerateMembersUtil.overriddenParameters(params, jvmElementFactory, javaCodeStyleManager, substitutor, originalPosition);
           }
 
-          final String paramsString = params.length == 1 ? params[0].getName() : "(" + StringUtil.join(params, new Function<PsiParameter, String>() {
+          String paramsString =
+            params.length == 1 ? getParamName(params[0], javaCodeStyleManager, originalPosition) : "(" + StringUtil.join(params, new Function<PsiParameter, String>() {
             @Override
             public String fun(PsiParameter parameter) {
-              return parameter.getName();
+              return getParamName(parameter, javaCodeStyleManager, originalPosition);
             }
-          }, ",") + ")";
+            }, ",") + ")";
+
+          final CodeStyleManager codeStyleManager = CodeStyleManager.getInstance(project);
+          PsiLambdaExpression lambdaExpression = (PsiLambdaExpression)JavaPsiFacade.getElementFactory(project)
+            .createExpressionFromText(paramsString + " -> {}", null);
+          lambdaExpression = (PsiLambdaExpression)codeStyleManager.reformat(lambdaExpression);
+          paramsString = lambdaExpression.getParameterList().getText();
           final LookupElementBuilder builder =
             LookupElementBuilder.create(paramsString).withPresentableText(paramsString + " -> {}").withInsertHandler(new InsertHandler<LookupElement>() {
               @Override
@@ -77,4 +85,8 @@ public class LambdaCompletionProvider extends CompletionProvider<CompletionParam
       }
     }
   }
+
+  private static String getParamName(PsiParameter param, JavaCodeStyleManager javaCodeStyleManager, PsiElement originalPosition) {
+    return javaCodeStyleManager.suggestUniqueVariableName(param.getName(), originalPosition, true);
+  }
 }