NullPointerException: Попытка вызвать виртуальный метод android.content.Context.getApplicationContext()»на объектную ссылку нулевой

Question

У меня есть Main-активность, которая выглядит как:

public class MainActivity extends Activity { 

ExpandableListAdapter listAdapter; 
ExpandableListView expListView; 
WeaponList listData = new WeaponList(); 
public static StatusCheck checkBombStatus = new StatusCheck(); 
String weapon = null; 
Intent openGameplay; 


@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 

    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); 

    // get the listview 
    expListView = (ExpandableListView) findViewById(R.id.expandableListView1); 

    // preparing list data 
    listData.prepareWeaponList(); 

    listAdapter = new ExpandableListAdapter(this, listData.listDataHeader, listData.listDataChild); 

    // setting list adapter 
    expListView.setAdapter(listAdapter); 

    //collapse all child-items from the listview 
    collapseItems(); 

    // Listview on child click listener  
    expListView.setOnChildClickListener(new OnChildClickListener() { 

     @Override 
     public boolean onChildClick(ExpandableListView parent, View v, 
            int groupPosition, int childPosition, long id) { 
      weapon = listData.listDataChild.get(listData.listDataHeader.get(groupPosition)).get(childPosition); 

      openGameplay = new Intent(MainActivity.this, GamePlay.class); 
      openGameplay.putExtra("weapon", weapon); 
      startActivity(openGameplay); 

      return false; 
     } 
    }); 
} 

private void collapseItems() { 

    expListView.expandGroup(0); 
    expListView.expandGroup(1); 
    expListView.expandGroup(2); 
    expListView.expandGroup(3); 
    expListView.expandGroup(4); 
    expListView.expandGroup(5); 
    expListView.expandGroup(6); 
    expListView.expandGroup(7); 
} 




public void exitApplication() { 
    this.finish(); 
} 

и моя вторая активность:

public class GamePlay extends Activity { 
... 
static MediaPlayer mediaPlayer = new MediaPlayer(); 
static SoundPool soundPool; 
static boolean loaded = false; 
private static Context mContext; 
public static StatusCheck statusCheck; 

public static Context getContext() { 
     return mContext; 
} 

    public void setContext(Context mContext) { 
     GamePlay.mContext = mContext; 
} 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.gameplay); 

    setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE); 

    Bundle extras = getIntent().getExtras();  

    ....  

    loadweapon(weapon = extras.getString("weapon")); 
    loadsound(); 

    imageView.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 

      if(j == 1) { 
       playAudioFromMediaPlayer(); 

      } 

      else { 
       //MediaPlayerService.loadAudioToSoundPool(getApplicationContext(), 54); 
      } 
     } 
    }); 

    reload.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      ... 
     } 
    }); 
} 


private void loadweapon(String weapon) { 

    if() .... 
} 


private void loadsound() { 
    if(j == 1 && soundID != 29) { 

     loadAudioToMediaPlayer(soundID); 
    } 
    else { 

     loadAudioToSoundPool(soundID); 
    } 
} 


public static void loadAudioToMediaPlayer(int id) { 

    soundID = id; 
    mediaPlayer = MediaPlayer.create(mContext.getApplicationContext(), SoundList.soundListfire.get(id)); 
} 

public static void loadAudioToSoundPool(int id) { 

    soundPool.setOnLoadCompleteListener(new OnLoadCompleteListener() { 
     @Override 
     public void onLoadComplete(SoundPool soundPool, int sampleId, int status) { 
     loaded = true; 
     } 
}); 
    soundID = soundPool.load(mContext.getApplicationContext(), SoundList.soundListfire.get(id), 1); 
} 

.... 
} 

Я имею следующее исключение, когда я нажимаю на Imageview:

03-11 12:01:20.199: E/AndroidRuntime(8929): java.lang.RuntimeException: Unable to start activity ComponentInfo{....GamePlay}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2329) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2391) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.ActivityThread.access$900(ActivityThread.java:147) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.os.Handler.dispatchMessage(Handler.java:102) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.os.Looper.loop(Looper.java:135) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.ActivityThread.main(ActivityThread.java:5256) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at java.lang.reflect.Method.invoke(Native Method) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at java.lang.reflect.Method.invoke(Method.java:372) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693) 
03-11 12:01:20.199: E/AndroidRuntime(8929): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at cs16.tacticalguns.GamePlay.loadAudioToMediaPlayer(GamePlay.java:442) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at cs16.tacticalguns.GamePlay.loadsound(GamePlay.java:423) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at cs16.tacticalguns.GamePlay.onCreate(GamePlay.java:72) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.Activity.performCreate(Activity.java:5938) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2282) 
03-11 12:01:20.199: E/AndroidRuntime(8929):  ... 10 more 

Я попытался заменить mContext.getApplicationContext() на this или Gameplay.this, но тогда у меня была ошибка Cannot use this in a static context. Что я делаю неправильно и как я могу это исправить?

Answer 1

Пропустите параметр контекста с методом loadAudioToSoundPool

private Context mContext; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.gameplay); 
    mContext=this; 


public static void loadAudioToSoundPool(Context mContext, int id) { 

    soundPool.setOnLoadCompleteListener(new OnLoadCompleteListener() { 
     @Override 
     public void onLoadComplete(SoundPool soundPool, int sampleId, int status) { 
     loaded = true; 
     } 
}); 
    soundID = soundPool.load(mContext, SoundList.soundListfire.get(id), 1); 
}