我正在尝试为MainScreen活动设置我的Navigation Drawer侦听器。设置完所有内容后，尝试使用ActionBarDrawerToggle时，我的应用就会崩溃。还有其他实现方法吗？
无法开始活动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
这是我活动中的一些代码：
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);
}
最佳答案
确保findViewById(R.id.mainDrawerLayout)和布局文件中的导航抽屉使用相同的ID。
调用mDrawerLayout时似乎.setDrawerListener()为空