将 onCreateOptionsMenu 结果删除到 NullPointerException答案

【问题标题】：removing onCreateOptionsMenu results to NullPointerException将 onCreateOptionsMenu 结果删除到 NullPointerException
【发布时间】：2013-11-25 08:51:43
【问题描述】：

我发现当我按下设备上的菜单按钮时，它给了我一个 NullPointerException。

 public boolean onCreateOptionsMenu(Menu menu) {
       getMenuInflater().inflate(R.menu.main, menu); //NullPointer Here
        return true;
    }

所以我所做的是通过删除上面的第二行并将返回类型更改为 false 来完全禁用菜单。但是，它仍然给我一个 NullPointerException。这是堆栈：

11-25 03:50:20.931    1212-1212/com.sblive.aufschoolbliz E/InputEventSender﹕ Exception dispatching finished signal.
11-25 03:50:20.931    1212-1212/com.sblive.aufschoolbliz E/MessageQueue-JNI﹕ Exception in MessageQueue callback: handleReceiveCallback
11-25 03:50:21.040    1212-1212/com.sblive.aufschoolbliz E/MessageQueue-JNI﹕ java.lang.NullPointerException
            at android.support.v7.app.ActionBarImplICS.getThemedContext(ActionBarImplICS.java:274)
            at android.support.v7.app.ActionBarActivityDelegate.getMenuInflater(ActionBarActivityDelegate.java:89)
            at android.support.v7.app.ActionBarActivity.getMenuInflater(ActionBarActivity.java:71)
            at android.app.Activity.onCreatePanelMenu(Activity.java:2505)
            at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:224)
            at android.support.v7.app.ActionBarActivity.superOnCreatePanelMenu(ActionBarActivity.java:224)
            at android.support.v7.app.ActionBarActivityDelegateICS.onCreatePanelMenu(ActionBarActivityDelegateICS.java:141)
            at android.support.v7.app.ActionBarActivity.onCreatePanelMenu(ActionBarActivity.java:199)
            at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.onCreatePanelMenu(ActionBarActivityDelegateICS.java:280)
            at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:413)
            at com.android.internal.policy.impl.PhoneWindow.onKeyDownPanel(PhoneWindow.java:795)
            at com.android.internal.policy.impl.PhoneWindow.onKeyDown(PhoneWindow.java:1471)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1867)
            at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3791)
            at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3774)
            at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
            at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
            at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
            at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483)
            at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
            at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540)
            at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
            at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
            at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
            at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
            at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
            at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
            at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
            at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3516)
            at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3666)
            at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:1982)
            at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1698)
            at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1689)
            at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:1959)
            at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
            at android.os.MessageQueue.nativePollOnce(Native Method)
            at android.os.MessageQueue.next(MessageQueue.java:132)
            at android.os.Looper.loop(Looper.java:124)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

11-25 03:50:21.040    1212-1212/com.sblive.aufschoolbliz D/AndroidRuntime﹕ Shutting down VM
11-25 03:50:21.040    1212-1212/com.sblive.aufschoolbliz W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41465700)
11-25 03:50:21.150    1212-1212/com.sblive.aufschoolbliz E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.NullPointerException
            at android.support.v7.app.ActionBarImplICS.getThemedContext(ActionBarImplICS.java:274)
            at android.support.v7.app.ActionBarActivityDelegate.getMenuInflater(ActionBarActivityDelegate.java:89)
            at android.support.v7.app.ActionBarActivity.getMenuInflater(ActionBarActivity.java:71)
            at android.app.Activity.onCreatePanelMenu(Activity.java:2505)
            at android.support.v4.app.FragmentActivity.onCreatePanelMenu(FragmentActivity.java:224)
            at android.support.v7.app.ActionBarActivity.superOnCreatePanelMenu(ActionBarActivity.java:224)
            at android.support.v7.app.ActionBarActivityDelegateICS.onCreatePanelMenu(ActionBarActivityDelegateICS.java:141)
            at android.support.v7.app.ActionBarActivity.onCreatePanelMenu(ActionBarActivity.java:199)
            at android.support.v7.app.ActionBarActivityDelegateICS$WindowCallbackWrapper.onCreatePanelMenu(ActionBarActivityDelegateICS.java:280)
            at com.android.internal.policy.impl.PhoneWindow.preparePanel(PhoneWindow.java:413)
            at com.android.internal.policy.impl.PhoneWindow.onKeyDownPanel(PhoneWindow.java:795)
            at com.android.internal.policy.impl.PhoneWindow.onKeyDown(PhoneWindow.java:1471)
            at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1867)
            at android.view.ViewRootImpl$ViewPostImeInputStage.processKeyEvent(ViewRootImpl.java:3791)
            at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3774)
            at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
            at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
            at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
            at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483)
            at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
            at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540)
            at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
            at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
            at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
            at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
            at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
            at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
            at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
            at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3516)
            at android.view.ViewRootImpl$ImeInputStage.onFinishedInputEvent(ViewRootImpl.java:3666)
            at android.view.inputmethod.InputMethodManager$PendingEvent.run(InputMethodManager.java:1982)
            at android.view.inputmethod.InputMethodManager.invokeFinishedInputEventCallback(InputMethodManager.java:1698)
            at android.view.inputmethod.InputMethodManager.finishedInputEvent(InputMethodManager.java:1689)
            at android.view.inputmethod.InputMethodManager$ImeInputEventSender.onInputEventFinished(InputMethodManager.java:1959)
            at android.view.InputEventSender.dispatchInputEventFinished(InputEventSender.java:141)
            at android.os.MessageQueue.nativePollOnce(Native Method)
            at android.os.MessageQueue.next(MessageQueue.java:132)
            at android.os.Looper.loop(Looper.java:124)
            at android.app.ActivityThread.main(ActivityThread.java:5103)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:525)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)

【问题讨论】：

正在尝试清理您的项目并重新构建..
检查您的应用程序中是否存在res/menu/main.xml 文件？
我的 res/menu/ 文件夹中有一个 main.xml
能否请您发布您的 main.xml 文件？

标签： java android nullpointerexception

【解决方案1】：

您的堆栈跟踪显示实际的 NPE 位于 ActionBarImplICS.java：

@Override
public Context getThemedContext() {
        return mActionBar.getThemedContext(); // here
}

可能有few reasons 为什么您的操作栏为空。

您没有在 onCreate() 中调用 setContentView() 吗？
您的清单中是否至少缺少 android:minSdkVersion="11"？
您是否使用android:theme="@style/Theme.NoTitle" 之类的主题？
您是否在使用android:windowIsFloating、android:backgroundDimEnabled 或android:windowNoTitle 等自定义样式？

编辑：如果没有标题/操作栏，解决此问题的最佳方法似乎是by overriding the menu key press。

【讨论】：

我正在使用没有标题栏的主题。如何在不使用带有标题栏的主题的情况下禁用选项？
在这种情况下，最好的方法是覆盖菜单按键：stackoverflow.com/a/19320065/1025599
如果我要使用 onKeyDown 方法，是否意味着我需要在我的应用程序的每个活动中覆盖菜单键？
您可以定义一个名为BaseActivity 的类来扩展Activity 并在那里定义方法。然后让所有其他活动扩展BaseActivity。
这样我们就不能使用选项菜单了，如果我们还需要支持显示选项菜单呢？

【解决方案2】：

 public boolean onCreateOptionsMenu(Menu menu) {
       getMenuInflater().inflate(R.menu.main, menu); //NullPointer Here
        return true;
    }

默认创建用于支持选项菜单。它膨胀了您可能尚未定义的指定“菜单 R.menu.main”。如果您希望继续支持选项菜单，请在 /res/menu 文件夹中定义一个菜单为“main.xml”，否则如果您不想支持选项菜单，只需删除整个方法。

【讨论】：

我的 res/menu 文件夹中有一个 menu.xml，但由于我不支持选项菜单，因此我更改了返回类型。我也尝试删除整个方法，但它也给了我一个错误..