ANDROID GPS/Invalid Listener

Question

我試圖從頭開始編寫一個GPS跟蹤器，但它只是在開始時纔會失敗。

出於某種原因，下面的代碼給了我一個IllegalArgumentException：invalid listener：null。

mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
mLocationManager.getProvider(LocationManager.GPS_PROVIDER); 
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1, mLocationListener); 

mLocationListener = new LocationListener() { 
    public void onLocationChanged(Location location) { 
      Log.i(TAG,"There is some noticeable movement"); 
     } 

     @Override 
     public void onProviderDisabled(String provider) { 
      // Auto-generated method stub 
     } 

     @Override 
     public void onProviderEnabled(String provider) { 
      // Auto-generated method stub 
     } 

     @Override 
     public void onStatusChanged(String provider, int status, Bundle extras) { 
      // Auto-generated method stub 
     } 
} 

任何線索？

Answer 1

，因爲在這條線

mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1, mLocationListener); 

的mLocationListener是null它。在requestLocationUpdates`之前初始化它。

mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
mLocationManager.getProvider(LocationManager.GPS_PROVIDER); 

mLocationListener = new LocationListener() { 
    public void onLocationChanged(Location location) { 
      Log.i(TAG,"There is some noticeable movement"); 
     } 

     @Override 
     public void onProviderDisabled(String provider) { 
      // Auto-generated method stub 
     } 

     @Override 
     public void onProviderEnabled(String provider) { 
      // Auto-generated method stub 
     } 

     @Override 
     public void onStatusChanged(String provider, int status, Bundle extras) { 
      // Auto-generated method stub 
     } 
} 
mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1, mLocationListener); 

Answer 2

更改代碼，

mLocationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
mLocationManager.getProvider(LocationManager.GPS_PROVIDER); 


mLocationListener = new LocationListener() { 
    public void onLocationChanged(Location location) { 
      Log.i(TAG,"There is some noticeable movement"); 
     } 

     @Override 
     public void onProviderDisabled(String provider) { 
      // Auto-generated method stub 
     } 

     @Override 
     public void onProviderEnabled(String provider) { 
      // Auto-generated method stub 
     } 

     @Override 
     public void onStatusChanged(String provider, int status, Bundle extras) { 
      // Auto-generated method stub 
     } 
} 

mLocationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 1000, 1, mLocationListener);