Android toast.makeText上下文错误

我无法在位置侦听器中调用toast.Maketext。上下文不可用，我做错了什么？Android toast.makeText上下文错误

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 

    } 

};

来源

2011-05-03 ProNeticas

试试这个Toast.makeText （getApplicationContext（），s，Toast.LENGTH_SHORT）.show（）; – 2011-05-03 09:00:22

我试过，我得到： **方法getApplicationContext（）是未定义的类型newLocationListener（）{} ** – ProNeticas 2011-05-03 09:04:01

我应该注意，这在** BroadcastReceiver **而不是** Activity ** – ProNeticas 2011-05-03 09:05:35

如果LocationListener声明是活动类（比如：MyActivity）里面，你应该创建Toast为：

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

万一LocationListener是在无上下文类中声明，就像在你案例a BroadcastReceiver，您可以将上下文传递给其构造函数：

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 
    } 
}

来源

2011-05-03 09:12:26 rekaszeru

这个答案怎么回事在BroadcastReceiver中没有活动 – 2015-08-26 12:17:40

@RikudoPain请详细说明您的问题，因为它不清楚。什么让你认为LocationListener的匿名实例没有在一个上下文组件中声明（这是一个常见的设计选择）？ – rekaszeru 2015-08-26 13:10:15

请阅读他的评论“我应该注意到这是在BroadcastReceiver而不是活动”，可能他忘了编辑这个问题。因为我对他有同样的问题 – 2015-08-26 13:19:00

确保您使用class.If你在活动中使用这种烤面包活动的背景下，写Classname.this到位情况下

的

来源

2011-05-03 09:17:57

由于上下文是不可用的，你可以通过它在构造函数中

来源

2012-03-27 15:39:55 vishesh

Android toast.makeText上下文错误

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