NullPointerException當創建一個新的對話框

Question

我有一個DialogFragment創建一個列表視圖和一個列表項目單擊我想顯示一個警告對話框，但是當我創建對話框時，它給了我一個NullPointerException帶有我從未見過的錯誤前

08-05 11:40:42.315: E/AndroidRuntime(4693): java.lang.NullPointerException 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at android.app.AlertDialog.resolveDialogTheme(AlertDialog.java:142) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at android.app.AlertDialog$Builder.<init>(AlertDialog.java:359) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at com.tyczj.bowling.dialogs.SeasonType$1$1.onClick(SeasonType.java:60) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at android.os.Handler.dispatchMessage(Handler.java:99) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at android.os.Looper.loop(Looper.java:137) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at android.app.ActivityThread.main(ActivityThread.java:4745) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at java.lang.reflect.Method.invokeNative(Native Method) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at java.lang.reflect.Method.invoke(Method.java:511) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
08-05 11:40:42.315: E/AndroidRuntime(4693):  at dalvik.system.NativeStart.main(Native Method) 

這裏是我的Dialog的onCreate

@Override 
public Dialog onCreateDialog(Bundle state){ 
    final Dialog d = new Dialog(getActivity()); 
    d.setContentView(R.layout.dialog_layout); 
    d.setTitle("Select a season"); 
    ListView lv = (ListView)d.findViewById(R.id.dialog_list); 
    String[] list = getResources().getStringArray(R.array.season_dialog_type); 
    lv.setAdapter(new ArrayAdapter<String>(getActivity(),R.layout.stats_list_layout,list)); 
    lv.setOnItemClickListener(new OnItemClickListener(){ 

     @Override 
     public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) { 
      d.dismiss(); 
      FragmentTransaction ft = getFragmentManager().beginTransaction(); 
      if(arg2 == 0){ 
       DialogFragment df = new SeasonsDialog(true); 
       df.show(ft,null); 
      }else if(arg2 == 1){ 
       AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); 
       final View v = getActivity().getLayoutInflater().inflate(R.layout.add_season_layout, null, false); 
       builder.setTitle("Add a season").setView(v).setPositiveButton("Add", new OnClickListener(){ 

        @Override 
        public void onClick(DialogInterface arg0, int arg1) { 
         arg0.dismiss(); 
         AlertDialog.Builder builder2 = new AlertDialog.Builder(getActivity()); //Error here 
         builder2.setTitle("Warning!").setMessage("Adding a new season will cause all new games to be under this season.\n\n Do you wish to continue?") 
         .setPositiveButton("Yes", new OnClickListener(){ 

          @Override 
          public void onClick(DialogInterface dialog,int which) { 
           dialog.dismiss(); 
           EditText et = (EditText)v.findViewById(R.id.editText1); 
           ContentValues values = new ContentValues(); 
           values.put(Games.SEASON, et.getText().toString()); 
           Uri uri = getActivity().getContentResolver().insert(Games.SEASONS_URI, values); 
           et.setText(""); 
           SharedPreferences pref = PreferenceManager.getDefaultSharedPreferences(getActivity()); 
           SharedPreferences.Editor edit = pref.edit(); 
           edit.putLong(Preferences.SELECTED_SEASON, ContentUris.parseId(uri)).commit(); 
          } 

         }).setNegativeButton("No", new OnClickListener(){ 

          @Override 
          public void onClick(DialogInterface dialog,int which) { 
           dialog.dismiss(); 
          } 

         }).create().show(); 
        } 

       }).setNegativeButton("Cancel", new OnClickListener(){ 

        @Override 
        public void onClick(DialogInterface dialog, int which) { 
         dialog.dismiss(); 
        } 

       }).create().show(); 
      } 

     } 

    }); 

    return d; 
} 

是錯誤的了，在這行我onClick

AlertDialog.Builder builder2 = new AlertDialog.Builder(getActivity()); 

那個錯誤是什麼意思？

Answer 1

這可能是因爲您試圖從onClick監聽器中調用getActivity（）。通常，匿名內部類只能訪問最終的。試圖權利之前創建監聽器做類似的東西

final Context context = getActivity(); 

，然後在該崩潰的線路上使用，而不是getActivity（）背景。

並作爲說明。我會在這裏使用DialogFragment。它更好地管理你的Dialog的生命週期。當您打開對話框時嘗試旋轉屏幕時，您會遇到問題。但是，使用DialogFragment，它會爲您處理此問題。

Answer 2

試試這個

AlertDialog alrt = (AlertDialog)arg0; 
AlertDialog.Builder builder = new AlertDialog.Builder(alrt.getContext()); 

顯示新的對話框後也駁回老對話框。