從onRetainNonConfigurationInstance（）獲取值的空指針異常 - Android

Question

我正在開發一個應用程序，它可以與不同的Mediaplayer實例同時播放2個音頻文件。要保留在屏幕上旋轉的媒體播放的狀態下實施的方法

public Object onRetainNonConfigurationInstance() 
      { 
        HashMap<String,Object> player = new HashMap<String,Object>(); 
        MediaPlayer instance = mp; 
        mp = null; 
        MediaPlayer instance1 = mp1; 
        mp1 = null; 
        player.put("mp", instance); 
        player.put("mp1", instance1); 
        return player; 

       } 

在的onCreate（），

HashMap<String, Object> playerhandle = (HashMap<String, Object>)getLastNonConfigurationInstance();    
        mp = (MediaPlayer)playerhandle.get("mp"); 
         if (mp == null) 
         { 
         mp = new MediaPlayer(); 
         } 
         mp1 = (MediaPlayer)playerhandle.get("mp1"); 
         if (mp1 == null) 
         { 
         mp1 = new MediaPlayer(); 
         } 

顯示在logcat的NullPointerException異常........

Answer 1

你從來不檢查如果playerhandle是null