调用方法从服务中更新活动中的TextViews

Question

我有一个应该从位置管理器接收当前位置的项目，然后更新显示这些坐标给用户的活动中的文字浏览。我们希望位置管理器在后台作为服务运行。目前，即使我打开了该活动，只要位置更新和更新textViews的方法从服务中调用，我们就会得到一个合力。我也无法将方法更改为静态方法，因为静态方法与textViews不兼容。下面是服务，被调用的方法和堆栈跟踪。

方法在服务时的位置变化活动

 public void onLocationChanged(Location location) { 
      currentLocation = location; 
      SplashActivity.historyList.add(currentLocation); 
      Toast.makeText(getApplicationContext(), "Point added", 
        Toast.LENGTH_SHORT).show(); 
      //postpones the update until NavigatorActivity starts 
      if (NavigatorStarted) { 
      new NavigatorActivity().doActionFine(currentLocation); 
      } 
      // these lines are controversial... 
      if (location.getAccuracy() > 1000 && location.hasAccuracy()) 
       locationManager.removeUpdates(this);       

     } 

中的方法是为了更新无论是从精确的GPS信号或粗略信号新位置文本视图时调用。使用do操作方法通过LocationService中当前位置的参数调用服务

public void updateLocationTextViewsFine(Location currentLocation) { 
    currentLatView = (TextView) findViewById(R.id.currentLat); 
    currentLonView = (TextView) findViewById(R.id.currentLon); 
    // update the textviews (labels) 
    String lat = currentLocation.getLatitude() + " (accurate)"; 
    String lon = currentLocation.getLongitude() + " (accurate)"; 
    currentLatView.setText(lat); 
    currentLonView.setText(lon); 
} 
public void updateLocationTextViewsCoarse(Location currentLocation) { 
    currentLatView = (TextView) findViewById(R.id.currentLat); 
    currentLonView = (TextView) findViewById(R.id.currentLon); 
    // update the textviews (labels) 
    String lat = currentLocation.getLatitude() + " (low accuracy)"; 
    String lon = currentLocation.getLongitude() + " (low accuracy)"; 
    currentLatView.setText(lat); 
    currentLonView.setText(lon); 
} 

public void doActionFine(Location currentLocation) { 
    updateLocationTextViewsFine(currentLocation); 
} 


public void doActionCoarse(Location currentLocation) { 
    updateLocationTextViewsCoarse(currentLocation); 
} 

收到新错误。

04-20 20:15:33.894: E/AndroidRuntime(4389): FATAL EXCEPTION: main 
04-20 20:15:33.894: E/AndroidRuntime(4389): java.lang.NullPointerException 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.app.Activity.findViewById(Activity.java:1637) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at com.example.UVAMapsProject.NavigatorActivity.updateLocationTextViewsFine(NavigatorActivity.java:341) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at com.example.UVAMapsProject.NavigatorActivity.doActionFine(NavigatorActivity.java:360) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at com.example.UVAMapsProject.LocationService$2.onLocationChanged(LocationService.java:116) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:191) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:124) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:140) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.os.Handler.dispatchMessage(Handler.java:99) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.os.Looper.loop(Looper.java:123) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at android.app.ActivityThread.main(ActivityThread.java:4627) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at java.lang.reflect.Method.invokeNative(Native Method) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at java.lang.reflect.Method.invoke(Method.java:521) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
04-20 20:15:33.894: E/AndroidRuntime(4389):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

这可以使用粘合剂来完成：

http://developer.android.com/guide/topics/fundamentals/bound-services.html

然后在活动中做到这一点在上述文章中的例子。连接到服务时，请询问当前位置（保存在“服务”或“首选项”中）。然后你给服务的听众，这将被称为。

这里有一些示例代码。缺少Listener和LocalService类的实现。但只是为了展示我的意思。

public class BindingActivity extends Activity { 
    LocalService mService; 
    boolean mBound = false; 

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

    @Override 
    protected void onStart() { 
     super.onStart(); 
     // Bind to LocalService 
     Intent intent = new Intent(this, LocalService.class); 
     bindService(intent, mConnection, Context.BIND_AUTO_CREATE); 
    } 

    @Override 
    protected void onStop() { 
     super.onStop(); 
     // Unbind from the service 
     if (mBound) { 
      mService.removeListener(this); 
      unbindService(mConnection); 
      mBound = false; 
     } 
    } 

    private ServiceConnection mConnection = new ServiceConnection() { 

     @Override 
     public void onServiceConnected(ComponentName className, 
       IBinder service) { 
      // We've bound to LocalService, cast the IBinder and get LocalService instance 
      LocalBinder binder = (LocalBinder) service; 
      mService = binder.getService(); 
      mBound = true; 

      handleLocation(mService.getCurrentLocation()); 
      mService.addListener(BindingActivity.this); 
     } 

     @Override 
     public void onServiceDisconnected(ComponentName arg0) { 
      mBound = false; 
     } 
    }; 
} 

活动结束后，您可以在解除绑定之前从服务中删除侦听器。

Answer 2

new NavigatorActivity().doActionFine(currentLocation); 

刚才看到这个....你正在创建一个活动的新实例并调用它的方法。这个新实例不是创建来打开你的锁的活动，这是一个没有生命周期方法的新活动。我肯定会转移到活页夹方案，如其他答案