introduce variable: suggest method reference expression (IDEA-102852)

java/java-impl/src/com/intellij/refactoring/introduceVariable/IntroduceVariableBase.java

@@ -197,9 +197,10 @@ public abstract class IntroduceVariableBase extends IntroduceHandlerBase {
     PsiExpression expression = PsiTreeUtil.getParentOfType(elementAtCaret, PsiExpression.class);
     while (expression != null) {
       if (!expressions.contains(expression) && !(expression instanceof PsiParenthesizedExpression) && !(expression instanceof PsiSuperExpression) && expression.getType() != PsiType.VOID) {
-        if (!(expression instanceof PsiReferenceExpression && (expression.getParent() instanceof PsiMethodCallExpression ||
-                                                               ((PsiReferenceExpression)expression).resolve() instanceof PsiClass))
-            && !(expression instanceof PsiAssignmentExpression)) {
+        if (expression instanceof PsiMethodReferenceExpression || 
+            !(expression instanceof PsiReferenceExpression &&
+             (expression.getParent() instanceof PsiMethodCallExpression || ((PsiReferenceExpression)expression).resolve() instanceof PsiClass)) &&
+            !(expression instanceof PsiAssignmentExpression)) {
           expressions.add(expression);
         }
       }

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

@@ -0,0 +1,9 @@
+class Foo {
+    interface I {
+        Integer[] _(int p);
+    }
+    void test() {
+        I m = Integer[]::new;
+        I i = m;
+    }
+}

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

@@ -0,0 +1,8 @@
+class Foo {
+    interface I {
+        Integer[] _(int p);
+    }
+    void test() {
+        I i = Integer[]:<caret>:new;
+    }
+}

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

@@ -392,6 +392,10 @@ public class IntroduceVariableTest extends LightCodeInsightTestCase {
     doTest(new MockIntroduceVariableHandler("i3", false, false, false, "int"));
   }
 
+  public void testMethodReferenceExpr() throws Exception {
+    doTest(new MockIntroduceVariableHandler("m", false, false, false, "Foo.I"));
+  }
+
   private void doTest(IntroduceVariableBase testMe) throws Exception {
     @NonNls String baseName = "/refactoring/introduceVariable/" + getTestName(false);
     configureByFile(baseName + ".java");