make Tab navigate to next parameter, if completion changes nothing

java/java-tests/testSrc/com/intellij/java/codeInsight/completion/CompletionHintsTest.java

@@ -691,6 +691,17 @@ public class CompletionHintsTest extends LightFixtureCompletionTestCase {
     checkHintContents(null);
   }
 
+  public void testNextParameterWorksWhenTabCompletionDoesntChangeAnything() throws Exception {
+    configureJava("class C { void m() { String local = \"a\"; String local2 = \"b\"; System.getPro<caret> } }");
+    complete("getProperty(String key, String def)");
+    type("local");
+    complete();
+    assertEquals("local", myFixture.getLookupElements()[0].getLookupString());
+    myFixture.performEditorAction(IdeActions.ACTION_CHOOSE_LOOKUP_ITEM_REPLACE);
+    waitForAllAsyncStuff();
+    checkResultWithInlays("class C { void m() { String local = \"a\"; String local2 = \"b\"; System.getProperty(<hint text=\"key:\"/>local, <HINT text=\"def:\"/><caret>) } }");
+  }
+
   private void checkResult(String text) {
     myFixture.checkResult(text);
   }

platform/lang-impl/src/com/intellij/codeInsight/hint/NextParameterAfterCompletionHandler.java

@@ -0,0 +1,56 @@
+// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.intellij.codeInsight.hint;
+
+import com.intellij.openapi.actionSystem.ActionManager;
+import com.intellij.openapi.actionSystem.DataContext;
+import com.intellij.openapi.actionSystem.IdeActions;
+import com.intellij.openapi.actionSystem.KeyboardShortcut;
+import com.intellij.openapi.editor.Caret;
+import com.intellij.openapi.editor.Editor;
+import com.intellij.openapi.editor.actionSystem.EditorActionHandler;
+import com.intellij.openapi.editor.actionSystem.EditorActionManager;
+import com.intellij.openapi.editor.event.DocumentEvent;
+import com.intellij.openapi.editor.event.DocumentListener;
+import com.intellij.openapi.util.Ref;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class NextParameterAfterCompletionHandler extends EditorActionHandler {
+  private final EditorActionHandler myOriginalHandler;
+
+  public NextParameterAfterCompletionHandler(EditorActionHandler originalHandler) {
+    myOriginalHandler = originalHandler;
+  }
+
+  @Override
+  protected boolean isEnabledForCaret(@NotNull Editor editor, @NotNull Caret caret, DataContext dataContext) {
+    return myOriginalHandler.isEnabled(editor, caret, dataContext);
+  }
+
+  @Override
+  protected void doExecute(@NotNull Editor editor, @Nullable Caret caret, DataContext dataContext) {
+    Ref<Boolean> documentChanged = new Ref<>();
+    DocumentListener listener = new DocumentListener() {
+      @Override
+      public void documentChanged(DocumentEvent event) {
+        if (event.getOldLength() > 0 || event.getNewLength() > 0) documentChanged.set(Boolean.TRUE);
+      }
+    };
+    editor.getDocument().addDocumentListener(listener);
+    try {
+      myOriginalHandler.execute(editor, caret, dataContext);
+    }
+    finally {
+      editor.getDocument().removeDocumentListener(listener);
+    }
+    if (documentChanged.isNull()) {
+      ActionManager actionManager = ActionManager.getInstance();
+      KeyboardShortcut completionShortcut = actionManager.getKeyboardShortcut(IdeActions.ACTION_CHOOSE_LOOKUP_ITEM_REPLACE);
+      KeyboardShortcut parameterShortcut = actionManager.getKeyboardShortcut(IdeActions.ACTION_EDITOR_NEXT_PARAMETER);
+      if (completionShortcut != null && completionShortcut.equals(parameterShortcut)) {
+        EditorActionHandler parameterHandler = EditorActionManager.getInstance().getActionHandler(IdeActions.ACTION_EDITOR_NEXT_PARAMETER);
+        if (parameterHandler.isEnabled(editor, caret, dataContext)) parameterHandler.execute(editor, caret, dataContext);
+      }
+    }
+  }
+}

resources/src/idea/RichPlatformPlugin.xml

@@ -387,6 +387,9 @@
     <experimentalFeature id="project.view.async.tree.model" internalFeature="true" percentOfUsers="10" requireRestart="true">
       <description>New implementation based on AsyncTreeModel + StructureTreeModel</description>
     </experimentalFeature>
+
+    <editorActionHandler action="EditorChooseLookupItemReplace" 
+                         implementationClass="com.intellij.codeInsight.hint.NextParameterAfterCompletionHandler"/>
   </extensions>
   <extensions defaultExtensionNs="org.jetbrains">
     <webServerRootsProvider implementation="org.jetbrains.builtInWebServer.ArtifactWebServerRootsProvider" order="last"/>