introduce variable: prefer expr type to expected when possible(IDEA-175248)

java/java-impl/src/com/intellij/refactoring/util/RefactoringUtil.java

@@ -357,7 +357,8 @@ public class RefactoringUtil {
 
   public static PsiType getTypeByExpressionWithExpectedType(PsiExpression expr) {
     PsiElementFactory factory = JavaPsiFacade.getInstance(expr.getProject()).getElementFactory();
-    PsiType type = getTypeByExpression(expr, factory);
+    PsiType typeByExpression = getTypeByExpression(expr, factory);
+    PsiType type = typeByExpression;
     final boolean isFunctionalType = LambdaUtil.notInferredType(type);
     final boolean isDenotable = PsiTypesUtil.isDenotableType(expr.getType());
     if (type != null && !isFunctionalType && isDenotable) {
@@ -365,6 +366,9 @@ public class RefactoringUtil {
     }
     ExpectedTypeInfo[] expectedTypes = ExpectedTypesProvider.getExpectedTypes(expr, false);
     if (expectedTypes.length == 1 || (isFunctionalType || !isDenotable)&& expectedTypes.length > 0 ) {
+      if (typeByExpression != null && Arrays.stream(expectedTypes).anyMatch(typeInfo -> typeInfo.getType().equals(typeByExpression))) {
+        return type;
+      }
       type = expectedTypes[0].getType();
       if (!type.equalsToText(CommonClassNames.JAVA_LANG_OBJECT)) return type;
     }

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

@@ -0,0 +1,17 @@
+
+import java.util.List;
+
+class CloseAction {
+  public void performAction() throws IOException {
+  }
+}
+
+class Foo {
+  void performAction() {
+  }
+
+  void bar(List<? extends Foo> f) {
+      Foo m = f.get(0);
+      m.performAction();
+  }
+}

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

@@ -0,0 +1,16 @@
+
+import java.util.List;
+
+class CloseAction {
+  public void performAction() throws IOException {
+  }
+}
+
+class Foo {
+  void performAction() {
+  }
+
+  void bar(List<? extends Foo> f) {
+    <selection>f.get(0)</selection>.performAction();
+  }
+}

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

@@ -567,6 +567,10 @@ public class IntroduceVariableTest extends LightCodeInsightTestCase {
     doTest(new MockIntroduceVariableHandler("m", false, false, false, "IA"));
   }
 
+  public void testChooseTypeExpressionWhenNotDenotable() throws Exception {
+    doTest(new MockIntroduceVariableHandler("m", false, false, false, "Foo"));
+  }
+
   private void doTest(IntroduceVariableBase testMe) {
     String baseName = "/refactoring/introduceVariable/" + getTestName(false);
     configureByFile(baseName + ".java");