introduce variable from lambda expression

java/java-psi-api/src/com/intellij/psi/LambdaUtil.java

@@ -117,7 +117,8 @@ public class LambdaUtil {
       final int parameterIndex = ((PsiParameterList)paramParent).getParameterIndex(param);
       if (parameterIndex > -1) {
         final PsiLambdaExpression lambdaExpression = PsiTreeUtil.getParentOfType(param, PsiLambdaExpression.class);
-        final PsiClassType.ClassResolveResult resolveResult = getFunctionInterfaceType(lambdaExpression);
+        final PsiType type = getFunctionInterfaceType(lambdaExpression);
+        final PsiClassType.ClassResolveResult resolveResult = type instanceof PsiClassType ? ((PsiClassType)type).resolveGenerics() : null;
         if (resolveResult != null) {
           final MethodSignature methodSignature = getFunction(resolveResult.getElement());
           if (methodSignature != null) {
@@ -140,7 +141,7 @@ public class LambdaUtil {
   }
 
   @Nullable
-  public static PsiClassType.ClassResolveResult getFunctionInterfaceType(@Nullable PsiLambdaExpression lambdaExpression) {
+  public static PsiType getFunctionInterfaceType(@Nullable PsiLambdaExpression lambdaExpression) {
     if (lambdaExpression != null) {
       final PsiElement parent = lambdaExpression.getParent();
       PsiType type = null;
@@ -177,10 +178,7 @@ public class LambdaUtil {
           type = method.getReturnType();
         }
       }
-
-      if (type instanceof PsiClassType) {
-        return ((PsiClassType)type).resolveGenerics();
-      }
+      return type;
     }
     return null;
   }

java/java-psi-api/src/com/intellij/psi/PsiLambdaExpressionType.java

@@ -57,7 +57,7 @@ public class PsiLambdaExpressionType extends PsiType {
 
   @Override
   public <A> A accept(@NotNull final PsiTypeVisitor<A> visitor) {
-    return visitor.visitType(this);
+    return visitor.visitLambdaExpressionType(this);
   }
 
   @Override

java/java-psi-api/src/com/intellij/psi/PsiTypeVisitor.java

@@ -67,4 +67,9 @@ public class PsiTypeVisitor<A> {
   public A visitDiamondType(PsiDiamondType diamondType) {
     return visitType(diamondType);
   }
+  
+  @Nullable
+  public A visitLambdaExpressionType(PsiLambdaExpressionType lambdaExpressionType) {
+    return visitType(LambdaUtil.getFunctionInterfaceType(lambdaExpressionType.getExpression()));
+  }
 }

java/java-tests/testData/refactoring/introduceVariable/LambdaExpr.after.java

@@ -0,0 +1,11 @@
+interface SAM<X> {
+        X m(int i, int j);
+    }
+
+class Foo {  
+    void test() {
+        SAM<Integer> c = (i, j)->i + j;
+        m(c);
+    }
+    void m(SAM<Integer> s) { }
+}

java/java-tests/testData/refactoring/introduceVariable/LambdaExpr.java

@@ -0,0 +1,10 @@
+interface SAM<X> {
+        X m(int i, int j);
+    }
+
+class Foo {  
+    void test() {
+        m(<selection>(i, j) -> i + j</selection>);
+    }
+    void m(SAM<Integer> s) { }
+}

java/java-tests/testData/refactoring/introduceVariable/LambdaExprNotAccepted.after.java

@@ -0,0 +1,11 @@
+interface SAM<X> {
+        X m(int i, int j);
+    }
+
+class Foo {  
+    void test() {
+        SAM<Integer> c = (i, j)->"" + i + j;
+        SAM<Integer> s3 = m(c);
+    }
+    <X> SAM<X> m(SAM<X> s) { return null; }
+}

java/java-tests/testData/refactoring/introduceVariable/LambdaExprNotAccepted.java

@@ -0,0 +1,10 @@
+interface SAM<X> {
+        X m(int i, int j);
+    }
+
+class Foo {  
+    void test() {
+      SAM<Integer> s3 = m(<selection>(i, j) -> "" + i + j</selection>);
+    }
+    <X> SAM<X> m(SAM<X> s) { return null; }
+}

java/java-tests/testSrc/com/intellij/refactoring/IntroduceVariableTest.java

@@ -335,6 +335,14 @@ public class IntroduceVariableTest extends LightCodeInsightTestCase {
     doTest(new MockIntroduceVariableHandler("c", false, false, false, CommonClassNames.JAVA_LANG_OBJECT));
   }
 
+  public void testLambdaExpr() throws Exception {
+    doTest(new MockIntroduceVariableHandler("c", false, false, false, "SAM<java.lang.Integer>"));
+  }
+
+  public void testLambdaExprNotAccepted() throws Exception {
+    doTest(new MockIntroduceVariableHandler("c", false, false, false, "SAM<java.lang.Integer>"));
+  }
+
   private void doTest(IntroduceVariableBase testMe) throws Exception {
     @NonNls String baseName = "/refactoring/introduceVariable/" + getTestName(false);
     configureByFile(baseName + ".java");