android - fragment 中的LocationListener

我可以在 fragment 管理器中使用LocationListener吗？实际上，当我使用它时，它在这一行中给了我错误:
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER,0,0, (android.location.LocationListener) this);
当我不将第四个参数强制转换为android.location.LocationListener时，会给我错误...

import android.content.Context;
import android.location.Location;
import android.location.LocationManager;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class Speedometer extends Fragment implements LocationListener {

    TextView txt;
    public Speedometer(){}

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.speedometer, container, false);

        txt=(TextView)rootView.findViewById(R.id.speedometer);

        LocationManager lm= (LocationManager)getActivity().getSystemService(Context.LOCATION_SERVICE);
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER,0,0, (android.location.LocationListener) this);

        return rootView;
    }

    @Override
    public void onLocationChanged(Location location) {

        if(location==null){
           txt.setText("-.- m/s");
        } else {
            float nCurrentSpeed=location.getSpeed();
            txt.setText(nCurrentSpeed+"m/s");
        }
    }
}

最佳答案

我认为您错误地实现了只有一个抽象方法 com.google.android.gms.location.LocationListener 的 onLocationChanged 接口(interface)

您应该实现具有 4 个抽象方法的 android.location.LocationListener
onLocationChanged(Location location) ,
onProviderDisabled(String provider) ,
onProviderEnabled(String provider) ,
onStatusChanged(String provider, int status, Bundle extras)