java - Android LocationListener 崩溃

Question

我正在尝试通过 ToggleButton 启用/禁用 GPS 服务。该应用程序以未选中的按钮启动，并且 GPS 服务被禁用(它们应该被禁用)。它们成功打开并且运行良好但是当我再次关闭它时，它崩溃了。这是代码:

    final LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
    final LocationListener locationListener = null;
    final ToggleButton gpsButton = (ToggleButton) findViewById(R.id.gpsButton);


    gpsButton.setOnClickListener(new OnClickListener() {

        public void onClick(View v) {
            // TODO Auto-generated method stub

            if (gpsButton.isChecked()) {
                 LocationListener locationListener = new LocationListener() {
                    public void onLocationChanged(Location location) {
                      // Called when a new location is found by the network location provider.

                        //doing some stuff with locations


                    }

                    public void onStatusChanged(String provider, int status, Bundle extras) {}

                    public void onProviderEnabled(String provider) {}

                    public void onProviderDisabled(String provider) {}
                  };
                  locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, seconds, 0, locationListener);
            }
            else {
                locationManager.removeUpdates(locationListener);
            }
        }

Answer 1

您在 onClickListener 之外声明了 locationListener，但随后在用户单击按钮时创建了一个新的本地 locationListener 变量。

当您尝试从中删除更新时，它仍然是 null，因为您创建了一个不同的变量。去掉onClick方法中locationListener的类型声明，所以变成了

...
if (gpsButton.isChecked()) {
    locationListener = new LocationListener() {
    ...