问题描述
我得到一个DrawerLayout无法转换，因此显示错误，我的应用崩溃了。
我是一名新的android开发人员，请帮帮我。
这是我的主要活动：
public class MainActivity extends AppCompatActivity {
private Toolbar toolbar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowHomeEnabled(true);
NavigationDrawerFragment drawerFragment = (NavigationDrawerFragment)
getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer);
drawerFragment.setUp((DrawerLayout) findViewById(R.id.drawer_layout),toolbar);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
这是Activitymain.xml：
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<include
android:id="@+id/app_bar"
layout="@layout/app_bar" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/app_bar"
android:text="@string/hello_world" />
</RelativeLayout>
<fragment
android:id="@+id/fragment_navigation_drawer"
android:name="com.appdego.rosesketch.NavigationDrawerFragment"
android:layout_width="@dimen/nav_drawer_width"
android:layout_height="match_parent"
android:layout_gravity="start"
app:layout="@layout/fragment_navigation_drawer"
tools:layout="@layout/fragment_navigation_drawer" />
</android.support.v4.widget.DrawerLayout>
我的NavigationDrawerFragment.java代码
public class NavigationDrawerFragment extends Fragment {
private ActionBarDrawerToggle mDrawerToggle;
private DrawerLayout mDrawerLayout;
public NavigationDrawerFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_navigation_drawer, container, false);
}
public void setUp(DrawerLayout drawerLayout, Toolbar toolbar) {
mDrawerLayout = drawerLayout;
mDrawerToggle = new ActionBarDrawerToggle(getActivity(), (DrawerLayout) drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) {
@Override
public void onDrawerOpened(View drawerView) {
super.onDrawerOpened(drawerView);
}
@Override
public void onDrawerClosed(View drawerView) {
super.onDrawerClosed(drawerView);
}
};
mDrawerLayout.setDrawerListener((DrawerListener) mDrawerLayout);
}
}
和fragment_navigation_drawer.xml：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.appdego.rosesketch.NavigationDrawerFragment">
<!-- TODO: Update blank fragment layout -->
<TextView android:layout_width="match_parent" android:layout_height="match_parent"
android:text="@string/hello_blank_fragment" />
</RelativeLayout>
日志猫：
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.appdego.rosesketch/com.appdego.rosesketch.MainActivity}: java.lang.ClassCastException: android.support.v4.widget.DrawerLayout cannot be cast to android.support.v4.widget.DrawerLayout$DrawerListener
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2338)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1321)
at android.os.Handler.dispatchMessage(Handler.java:110)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5292)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassCastException: android.support.v4.widget.DrawerLayout cannot be cast to android.support.v4.widget.DrawerLayout$DrawerListener
at com.appdego.rosesketch.NavigationDrawerFragment.setUp(NavigationDrawerFragment.java:49)
at com.appdego.rosesketch.MainActivity.onCreate(MainActivity.java:25)
at android.app.Activity.performCreate(Activity.java:5264)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1088)
我遵循滑模材料设计教程。
1楼
问题在以下行中： mDrawerLayout.setDrawerListener((DrawerListener) mDrawerLayout);
您需要设置一个侦听器，但是您正在将DrawerLayout类型转换为DrawerListener 。
我建议您完全删除该行，因为不需要。 如果您确实要设置一个侦听器，则应按以下步骤进行：
mDrawerLayout.setDrawerListener(new DrawerLayout.DrawerListener() {
@Override
public void onDrawerSlide(View drawerView, float slideOffset) {
}
@Override
public void onDrawerOpened(View drawerView) {
}
@Override
public void onDrawerClosed(View drawerView) {
}
@Override
public void onDrawerStateChanged(int newState) {
}
});
2楼
您需要在下面进行代码更改：
// Set the drawer toggle as the DrawerListener
mDrawerLayout.setDrawerListener(mDrawerToggle);