Question

使用库slidingmenu和actionbarsherlock我尝试编写代码以使操作栏中的图标可单击，但我在崩溃时出错。这是切换代码：

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
        menu.toggle();
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

logcat说：

10-01 15:18:00.134: E/AndroidRuntime(27038): FATAL EXCEPTION: main
10-01 15:18:00.134: E/AndroidRuntime(27038): java.lang.NullPointerException
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.db.batt.MainActivity.onOptionsItemSelected(MainActivity.java:512)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.support.v4.app.Watson.onMenuItemSelected(Watson.java:118)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.actionbarsherlock.ActionBarSherlock.callbackOptionsItemSelected(ActionBarSherlock.java:604)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.actionbarsherlock.internal.ActionBarSherlockNative.dispatchOptionsItemSelected(ActionBarSherlockNative.java:92)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.actionbarsherlock.app.SherlockFragmentActivity.onMenuItemSelected(SherlockFragmentActivity.java:204)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.android.internal.widget.ActionBarView$3.onClick(ActionBarView.java:171)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.view.View.performClick(View.java:4247)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.view.View$PerformClick.run(View.java:17733)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.os.Handler.handleCallback(Handler.java:730)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.os.Handler.dispatchMessage(Handler.java:92)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.os.Looper.loop(Looper.java:137)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at android.app.ActivityThread.main(ActivityThread.java:5323)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at java.lang.reflect.Method.invokeNative(Native Method)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at java.lang.reflect.Method.invoke(Method.java:525)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:743)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:559)
10-01 15:18:00.134: E/AndroidRuntime(27038):    at dalvik.system.NativeStart.main(Native Method)

我该如何解决？

编辑：我onCreate中的滑动菜单

SlidingMenu menu;
        menu = new SlidingMenu(this);
        menu.setMode(SlidingMenu.LEFT);
        menu.setTouchModeAbove(SlidingMenu.TOUCHMODE_FULLSCREEN);
        menu.setShadowWidth(50);
        menu.setFadeDegree(0.30f);
        menu.setSlidingEnabled(true);
        menu.attachToActivity(this, SlidingMenu.SLIDING_CONTENT);
        menu.setBehindWidth(420);
        menu.setMenu(R.layout.menu_frame);
        //getActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

所以menu声明不是吗？

Answer 1

我敢打赌，你没有初始化menu变量，这一行.-

 menu.toggle();

抛出NullPointerException。

修改

您在menu中声明了一个局部变量onCreate，但尝试访问onOptionsItemSelected中的实例变量。删除该行.-

SlidingMenu menu;

单击带有滑动菜单的菜单图标时崩溃

1 个答案: