旋轉屏幕或最小化應用程序時，碎片崩潰

Question

我將從第一個片段到第二個。當我旋轉或最小化第二個片段上的屏幕時，應用程序崩潰。早些時候，當我用最小化的應用程序第一個片段被稱爲（不知道爲什麼），現在它的崩潰這裏是代碼：

2nd Fragment : 
public class SubPlaceFragment extends Fragment { 

    public static final String LOG_TAG = SubPlaceFragment.class.getSimpleName(); 

    private OnFragmentInteractionListener mListener; 

    public SubPlaceFragment() { 
     // Required empty public constructor 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     return inflater.inflate(R.layout.fragment_sub_place, container, false); 
    } 

    @Override 
    public void onAttach(Activity activity) { 
     super.onAttach(activity); 

    } 

    @Override 
    public void onDetach() { 
     super.onDetach(); 
     mListener = null; 
    } 

    @Override 
    public void onPause() { 
     super.onPause(); 
     Log.i(LOG_TAG,"onPause"); 
    } 

    @Override 
    public void onResume() { 
     super.onResume(); 
     Log.i(LOG_TAG, "onResume"); 
    } 

    @Override 
    public void onStop() { 
     super.onStop(); 
     Log.i(LOG_TAG, "onStop"); 
    } 

    @Override 
    public void onStart() { 
     super.onStart(); 
     Log.i(LOG_TAG, "onStart"); 
    } 

    @Override 
    public void onActivityCreated(Bundle savedInstanceState) { 
     super.onActivityCreated(savedInstanceState); 
     Log.i(LOG_TAG, "onActivityCreated"); 
    } 

    public interface OnFragmentInteractionListener { 
     // TODO: Update argument type and name 
     void onFragmentInteraction(Uri uri); 
    } 
} 

這是我的logcat：

E/AndroidRuntime: FATAL EXCEPTION: main 
                       Process: com.example.manish.planetdelhi, PID: 16516 
                       java.lang.RuntimeException: Unable to resume activity {com.example.manish.planetdelhi/com.example.manish.planetdelhi.MainActivity}: java.lang.ClassCastException: com.example.manish.planetdelhi.SubPlaceFragment cannot be cast to com.example.manish.planetdelhi.PlaceListFragment 
                        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2812) 
                        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2845) 
                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1252) 
                        at android.os.Handler.dispatchMessage(Handler.java:102) 
                        at android.os.Looper.loop(Looper.java:136) 
                        at android.app.ActivityThread.main(ActivityThread.java:5086) 
                        at java.lang.reflect.Method.invokeNative(Native Method) 
                        at java.lang.reflect.Method.invoke(Method.java:515) 
                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 
                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
                        at dalvik.system.NativeStart.main(Native Method) 
                       Caused by: java.lang.ClassCastException: com.example.manish.planetdelhi.SubPlaceFragment cannot be cast to com.example.manish.planetdelhi.PlaceListFragment 
                        at com.example.manish.planetdelhi.MainActivity.AddPlaceFragment(MainActivity.java:74) 
                        at com.example.manish.planetdelhi.MainActivity.onStart(MainActivity.java:80) 
                        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1194) 
                        at android.app.Activity.performStart(Activity.java:5258) 
                        at android.app.Activity.performRestart(Activity.java:5314) 
                        at android.app.Activity.performResume(Activity.java:5319) 
                        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:2797) 
                        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:2845)  
                        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1252)  
                        at android.os.Handler.dispatchMessage(Handler.java:102)  
                        at android.os.Looper.loop(Looper.java:136)  
                        at android.app.ActivityThread.main(ActivityThread.java:5086)  
                        at java.lang.reflect.Method.invokeNative(Native Method)  
                        at java.lang.reflect.Method.invoke(Method.java:515)  
                        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)  
                        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)  
                        at dalvik.system.NativeStart.main(Native Method)  

這是我的全力主要活動代碼：

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
         .setAction("Action", null).show(); 
      } 
     }); 
     AddPlaceFragment(savedInstanceState); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
    } 

    @Override 
    protected void onSaveInstanceState(Bundle outState) { 
     super.onSaveInstanceState(outState); 
    } 

    private void AddPlaceFragment(Bundle loadingFirstTime) 
    { 
     // calling placeListFragment for the first time 
     if (loadingFirstTime == null) { 
      FragmentManager fragmentManager = getFragmentManager(); 
      FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 
      fragmentTransaction.add(R.id.fragment_container, placeListFragment).addToBackStack(placeListFragment.getTag()); 
      fragmentTransaction.commit(); 
     } 
    } 

    // calling placeListFragment when screen is rotated 
    private void AddPlaceFragment() 
    { 
     placeListFragment = (PlaceListFragment) getFragmentManager().findFragmentById(R.id.fragment_container); 
    } 

    @Override 
    protected void onStart() { 
     super.onStart(); 
     AddPlaceFragment(); 
    } 

    @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); 
    } 

    @Override 
    public void onBackPressed() { 
     int fragmentCount = getFragmentManager().getBackStackEntryCount(); 
     if(fragmentCount > 1) 
     { 
     getFragmentManager().popBackStack(); 
     } 
     else { 
      finish(); 
     } 
    } 

    @Override 
    public void DelhiPlaceClicked(int paramInt, String paramString) // meathod invoked from placelistfragment 
    { 
     Bundle localBundle = new Bundle(); 
     localBundle.putInt("_id", paramInt); 
     localBundle.putString("sub_place_name", paramString); 
     SubPlaceFragment subfragment = new SubPlaceFragment(); 
     subfragment.setArguments(localBundle); 
     FragmentManager fragmentManager = getFragmentManager(); 
     FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction(); 
     fragmentTransaction.replace(R.id.fragment_container, subfragment).addToBackStack(subfragment.getTag()); 
     fragmentTransaction.commit(); 
    } 

感謝您的幫助:)

Answer 1

你加入你的通過：

fragmentTransaction.replace(R.id.fragment_container, subfragment) 

現在，一個以呼叫：

getFragmentManager().findFragmentById(R.id.fragment_container); 

將返回你只subfragment。因此，您可以分享您的主要活動代碼