extract method: inline output variable if it is returned right after creation ( IDEA-54490 )

java/java-impl/src/com/intellij/refactoring/extractMethod/ExtractMethodProcessor.java

@@ -33,6 +33,7 @@ import com.intellij.openapi.editor.colors.EditorColors;
 import com.intellij.openapi.editor.colors.EditorColorsManager;
 import com.intellij.openapi.editor.markup.TextAttributes;
 import com.intellij.openapi.project.Project;
+import com.intellij.openapi.util.Comparing;
 import com.intellij.openapi.util.Pair;
 import com.intellij.openapi.util.TextRange;
 import com.intellij.openapi.vfs.VirtualFile;
@@ -598,7 +599,23 @@ public class ExtractMethodProcessor implements MatchProvider {
         body.add(myElementFactory.createStatementFromText("return false;", null));
       }
       else if (!myHasReturnStatement && hasNormalExit && myOutputVariable != null) {
-        body.add(returnStatement);
+        final PsiReturnStatement insertedReturnStatement = (PsiReturnStatement)body.add(returnStatement);
+        if (myOutputVariables.length == 1) {
+          final PsiExpression returnValue = insertedReturnStatement.getReturnValue();
+          if (returnValue instanceof PsiReferenceExpression) {
+            final PsiElement resolved = ((PsiReferenceExpression)returnValue).resolve();
+            if (resolved instanceof PsiLocalVariable && Comparing.strEqual(((PsiVariable)resolved).getName(), outVariableName)) {
+              final PsiStatement statement = PsiTreeUtil.getPrevSiblingOfType(insertedReturnStatement, PsiStatement.class);
+              if (statement instanceof PsiDeclarationStatement) {
+                final PsiElement[] declaredElements = ((PsiDeclarationStatement)statement).getDeclaredElements();
+                if (ArrayUtil.find(declaredElements, resolved) != -1) {
+                  InlineUtil.inlineVariable((PsiVariable)resolved, ((PsiVariable)resolved).getInitializer(), (PsiReferenceExpression)returnValue);
+                  resolved.delete();
+                }
+              }
+            }
+          }
+        }
       }
       if (myNullConditionalCheck) {
         final String varName = myOutputVariable.getName();

java/java-tests/testData/refactoring/extractMethod/CodeDuplicatesWithOutputValue_after.java

@@ -12,8 +12,7 @@ class C {
     }
 
     private List newMethod(Object[] array) {
-        List l1 = new ArrayList(Arrays.asList(array));
-        return l1;
+        return new ArrayList(Arrays.asList(array));
     }
 
     String[] getObjects() {

java/java-tests/testData/refactoring/extractMethod/FinalOutputVar_after.java

@@ -7,7 +7,6 @@ class C {
     }
 
     private int newMethod() {
-        final int i = 128;
-        return i;
+        return 128;
     }
 }

java/java-tests/testData/refactoring/extractMethod/InlineCreated2ReturnLocalVariablesOnly.java

@@ -0,0 +1,8 @@
+class Test {
+    void foo() {
+      <selection>int j = 0;
+      int i = 0;
+      j = 9;</selection>
+      System.out.println(i);
+    }
+}

java/java-tests/testData/refactoring/extractMethod/InlineCreated2ReturnLocalVariablesOnly_after.java

@@ -0,0 +1,13 @@
+class Test {
+    void foo() {
+        int i = newMethod();
+      System.out.println(i);
+    }
+
+    private int newMethod() {
+        int j = 0;
+        int i = 0;
+        j = 9;
+        return i;
+    }
+}

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

@@ -257,6 +257,10 @@ public class ExtractMethodTest extends LightCodeInsightTestCase {
     doTest();
   }
 
+  public void testInlineCreated2ReturnLocalVariablesOnly() throws Exception {
+    doTest();
+  }
+
   public void testGuardMethodDuplicates() throws Exception {
     doDuplicatesTest();
   }