Android toast.makeText上下文錯誤

我無法在位置偵聽器中調用toast.Maketext。上下文不可用，我做錯了什麼？Android toast.makeText上下文錯誤

private LocationListener ll = new LocationListener() { 

    public void onLocationChanged(Location l) { 
     // SMSReceiver.l = l; 
     String s = ""; 
     s += "\tTime: " + l.getTime() + "\n"; 
     s += "\tLatitude: " + l.getLatitude() + "°\n"; 
     s += "\tLongitude: " + l.getLongitude() + "°\n"; 
     s += "\tAccuracy: " + l.getAccuracy() + " metres\n"; 
     s += "\tAltitude: " + l.getAltitude() + " metres\n"; 
     s += "\tSpeed: " + l.getSpeed() + " metres\n"; 

     // TODO Auto-generated method stub 
     if (l.hasSpeed()) { 
      mySpeed = l.getSpeed(); 
     } 

     Log.i(DEBUG_TAG, "On Location Changed: (" + s + ")"); 
ERROR HERE-->  Toast.makeText(context, s, Toast.LENGTH_SHORT).show(); 
    } 

    public void onProviderDisabled(String arg0) { 
     // TODO Auto-generated method stub 

    } 

    public void onProviderEnabled(String arg0) { 
     // TODO Auto-generated method stub 

    } 

    public void onStatusChanged(String arg0, int arg1, Bundle arg2) { 
     // TODO Auto-generated method stub 

    } 

};

來源

2011-05-03 ProNeticas

試試這個Toast.makeText （getApplicationContext（），s，Toast.LENGTH_SHORT）.show（）; – 2011-05-03 09:00:22

我試過，我得到： **方法getApplicationContext（）是未定義的類型newLocationListener（）{} ** – ProNeticas 2011-05-03 09:04:01

我應該注意，這在** BroadcastReceiver **而不是** Activity ** – ProNeticas 2011-05-03 09:05:35

如果LocationListener聲明是活動類（比如：MyActivity）裏面，你應該創建Toast爲：

Toast.makeText(MyActivity.this, s, Toast.LENGTH_SHORT).show();

萬一LocationListener是在無上下文類中聲明，就像在你案例a BroadcastReceiver，您可以將上下文傳遞給其構造函數：

private final class MyReceiver extends BroadcastReceiver 
{ 
    private MyLocationListener listener; 
    public MyReceiver(final Context context) 
    { 
     this.listener = new MyLocationListener(context); 
    } 

    private final class MyLocationListener implements LocationListener 
    { 
     private Context context; 
     public MyLocationListener(final Context context) 
     { 
      this.context = context; 
     } 

     @Override 
     public void onLocationChanged(Location location) 
     { 
      // ... 
      Toast.makeText(context, "Toast message here", Toast.LENGTH_SHORT).show(); 
     } 

     // implement the rest of the methods 
    } 

    @Override 
    public void onReceive(Context context, Intent intent) 
    { 
     // Note that you have a context here, which you can use when receiving an broadcast message 
    } 
}

來源

2011-05-03 09:12:26 rekaszeru

這個答案怎麼回事在BroadcastReceiver中沒有活動 – 2015-08-26 12:17:40

@RikudoPain請詳細說明您的問題，因爲它不清楚。什麼讓你認爲LocationListener的匿名實例沒有在一個上下文組件中聲明（這是一個常見的設計選擇）？ – rekaszeru 2015-08-26 13:10:15

請閱讀他的評論「我應該注意到這是在BroadcastReceiver而不是活動」，可能他忘了編輯這個問題。因爲我對他有同樣的問題 – 2015-08-26 13:19:00

確保您使用class.If你在活動中使用這種烤麪包活動的背景下，寫Classname.this到位情況下

的

來源

2011-05-03 09:17:57

由於上下文是不可用的，你可以通過它在構造函數中

來源

2012-03-27 15:39:55 vishesh

Android toast.makeText上下文錯誤

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