無法訪問Android上的另一個線程資源（崩潰）

Question

這一直讓我瘋狂幾天，我是新來的android，我似乎無法弄清楚如何訪問其他線程的資源。我試圖安排一段時間後執行任務，這裏是有關的代碼：

公共類TikTakBoom延伸活動{

private SensorManager mSensorManager; 

public ToggleButton startButton; 

private Bitmap mBombOn; 
private Bitmap mBombOff; 

/** Tik tak boom **/ 
protected MediaPlayer mediaPlayer;  // play tik tak or boom 
protected Timer boomTimer;    // timer for explosion 

// bomb button backgrounds 
protected android.graphics.drawable.BitmapDrawable buttonBombOn; 
protected android.graphics.drawable.BitmapDrawable buttonBombOff; 

// random boom delay in ms 
protected long boomDelay = 1500; 

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

    requestWindowFeature(Window.FEATURE_NO_TITLE); 

    // tell system to use the layout defined in our XML file 
    setContentView(R.layout.main); 

    Log.w(this.getClass().getName(), "SIS is null"); 

    // configure toggle button (bomb on/off) 
    startButton = (ToggleButton)findViewById(R.id.toggleButton1); 
    startButton.setText(""); 
    startButton.setTextOn(""); 
    startButton.setTextOff(""); 

    // scale bomb images to button size 
    mBombOff = BitmapFactory.decodeResource(this.getResources(), R.drawable.bomb_off); 
    mBombOff = Bitmap.createScaledBitmap(mBombOff, 120, 120, true); 

    mBombOn = BitmapFactory.decodeResource(this.getResources(), R.drawable.bomb_on); 
    mBombOn = Bitmap.createScaledBitmap(mBombOn, 120, 120, true); 

    buttonBombOn = new android.graphics.drawable.BitmapDrawable(mBombOn); 
    buttonBombOff = new android.graphics.drawable.BitmapDrawable(mBombOff); 

    startButton.setChecked(false); 

    boomTimer = new Timer(); 

    // onclick listener for toggle bomb on/off 
    startButton.setOnClickListener(new OnClickListener() { 
     public void onClick(View v) { 
      // Perform action on clicks 
      if (startButton.isChecked()) { 
       mediaPlayer = MediaPlayer.create(getApplicationContext(), R.raw.tik_tak); 

       mediaPlayer.setLooping(true); 
       mediaPlayer.start(); 

       // align boom delay with tik tak duration 
       boomDelay -= boomDelay%mediaPlayer.getDuration(); 

       boomTimer.schedule(new BoomTimeTask(getApplicationContext()), boomDelay); 

       startButton.setBackgroundDrawable(buttonBombOn); 
      } else { 
       if (mediaPlayer != null) { 
        mediaPlayer.release(); 
        mediaPlayer = null; 
       } 

       startButton.setBackgroundDrawable(buttonBombOff); 
      } 
     } 

    }); 
} 

class BoomTimeTask extends TimerTask { 
    Context context; 

    public BoomTimeTask(Context context) { 
     super(); 

     this.context = context; 
    } 

    public void run() { 
     if (mediaPlayer != null) { 
      mediaPlayer.release(); 
      mediaPlayer = null; 
     } 

     mediaPlayer = MediaPlayer.create(getApplicationContext(), R.raw.sheldon); 

     mediaPlayer.setLooping(false); 
     mediaPlayer.start(); 

     startButton = (ToggleButton)((Activity)context).findViewById(R.id.toggleButton1); 

     startButton.setChecked(false); 
     //startButton.setBackgroundDrawable(buttonBombOff); 
    } 
} 

應用在BoomTimeTask.run()startButton.setChecked(false)崩潰，我猜測空指針異常。

請幫助，我要去瘋了，我已經嘗試了一切！沒有任何作品..嘗試它沒有作爲參數傳遞的上下文，因爲參考應該可以看到BoomTimeTask線程，嘗試了十幾個其他的東西，只是無法讓它的工作。

我在想什麼？ Thx提前，真的會很感激任何幫助。乾杯，瓦爾。

解決：how to change button text dynamically for every 3 sec in android?

Answer 1

您應該使用

runOnUiThread(new Runnable() { 
    public void run() { 
    // YOUR ACTIONS ON Graphic interface 
    } 
}); 

這是因爲在Android中你不能修改GUI元素，而在與GUI處理線程之中。

http://developer.android.com/reference/android/app/Activity.html