Android 应用程序因 ActionBarDrawerToggle 而崩溃

Question

我正在尝试为我的 MainScreen Activity 设置 Navigation Drawer 监听器。当我设置好所有内容后，当我尝试使用 ActionBarDrawerToggle 时我的应用程序崩溃了。还有其他实现方法吗？

Unable to start activity ComponentInfo{koeksworld.com.firstandroidproject/koeksworld.com.firstandroidproject.UserMainPanel}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.widget.DrawerLayout.setDrawerListener(android.support.v4.widget.DrawerLayout$DrawerListener)' on a null object reference

这是我 Activity 中的一些代码:

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_user_main_panel);
    listener = new NavigationDrawerItemListener(this);
    Toolbar toolbar = (Toolbar) findViewById(R.id.groceryAppHomeToolbar);
    homeDrawer = (DrawerLayout) findViewById(R.id.mainDrawerLayout);
    homeListView = (ListView) findViewById(R.id.homeListView);
    homeListView.setBackgroundColor(getResources().getColor(R.color.colorBlue));
    navigationArray = getResources().getStringArray(R.array.navigationArray);
    navigationAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1,
            navigationArray);
    homeListView.setAdapter(navigationAdapter);
    homeListView.setOnItemClickListener(listener);
    //The suspected culprit
    drawerListener = new ActionBarDrawerToggle(this, homeDrawer, toolbar, R
            .string
            .open_drawer, R
            .string.close_Drawer);
    homeDrawer.setDrawerListener(drawerListener);
    drawerListener.syncState();
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);

}

Answer 1

确保在 findViewById(R.id.mainDrawerLayout) 和布局文件中为 navigation drawer 使用相同的 id。

似乎 mDrawerLayout 在调用 .setDrawerListener() 时为空