不幸的是，当我要推送片段时，Android已停止

Question

If I want to change fragment when user has selected some elements of menu (android navigation drawer) my app crashing.

Here is my fragment class code

@SuppressLint("NewApi")
public class InboxActivity extends Fragment
{
    @Override

    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        return inflater.inflate(R.layout.inbox_fragment, container, false);

    }

}

It's very simple code.

Here what i do on my main class with drawer:

private void selectItem(int position) {


    Fragment f;
    if(position == 1)
    {
        f = new InboxActivity();
        FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction ft = fragmentManager.beginTransaction();
        ft.replace(R.id.content_frame, f);
        ft.commit();

        Intent activity = new Intent(getApplicationContext(), InboxActivity.class);
        startActivity(activity);                
    }
}

It is very simple code too. And here is my errors:

04-22 11:18:25.830: E/AndroidRuntime(25512): FATAL EXCEPTION: main
04-22 11:18:25.830: E/AndroidRuntime(25512): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.navigationdrawerexample/com.example.android.navigationdrawerexample.InboxActivity}: java.lang.ClassCastException: com.example.android.navigationdrawerexample.InboxActivity cannot be cast to android.app.Activity
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2299)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.ActivityThread.access$700(ActivityThread.java:154)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1284)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.os.Handler.dispatchMessage(Handler.java:99)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.os.Looper.loop(Looper.java:137)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.ActivityThread.main(ActivityThread.java:5306)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at java.lang.reflect.Method.invokeNative(Native Method)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at java.lang.reflect.Method.invoke(Method.java:511)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at dalvik.system.NativeStart.main(Native Method)
04-22 11:18:25.830: E/AndroidRuntime(25512): Caused by: java.lang.ClassCastException: com.example.android.navigationdrawerexample.InboxActivity cannot be cast to android.app.Activity
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.Instrumentation.newActivity(Instrumentation.java:1071)
04-22 11:18:25.830: E/AndroidRuntime(25512):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2166)
04-22 11:18:25.830: E/AndroidRuntime(25512):    ... 11 more

What am I doing wrong?

Answer 1

As stated in your logcat output

java.lang.ClassCastException: com.example.android.navigationdrawerexample.InboxActivity cannot be cast to android.app.Activity

You're trying to start your fragment as an activity

Intent activity = new Intent(getApplicationContext(), InboxActivity.class);
startActivity(activity);

You should remove those two lines as your fragment has already been added using a FragmentTransaction .

Answer 2

You're doing a bit of overkill here. First, you create the fragment and replace it through a transaction, which is all correct. However after that, you're trying to start your fragment class as an activity. A fragment is not an activity, so that's why you get this in your error log:

Caused by: java.lang.ClassCastException: com.example.android.navigationdrawerexample.InboxActivity cannot be cast to android.app.Activity

The solution is fairly simple, just remove these two lines:

    Intent activity = new Intent(getApplicationContext(), InboxActivity.class);
    startActivity(activity);

Protip: rename InboxActivity to InboxFragment . Confusing names are the worst. ;-)

Answer 3

public class InboxActivity extends Fragment

您的InboxActivity应该扩展Activity以便以您尝试的方式启动它