android - 获取我的位置没有用

Question

我在获取我的位置时遇到空异常错误我在我的 list 中放了一个使用权限

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.INTERNET"/>

任何人都可以帮助我弄清楚这有什么问题我是 android 开发的新手。提前致谢 。

代码:

    package com.example.locationsample;

    import java.io.IOException;
    import java.util.List;
    import java.util.Locale;

    import android.location.Address;
    import android.location.Geocoder;
    import android.location.Location;
    import android.location.LocationListener;
    import android.location.LocationManager;
    import android.os.Build;
    import android.os.Bundle;
    import android.annotation.TargetApi;
    import android.app.Activity;
    import android.content.Context;
    import android.util.Log;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.TextView;
    import android.widget.Toast;

    public class MainActivity extends Activity {
    Button getloc;//`Location Button`
    TextView lati;
    TextView longi;
    TextView address;

    LocationManager location_manager;
    String getLatitude;
    String getLongitude;

    double x;
    double y;

    Geocoder geocoder;
    List<Address> addresses;
    Location loc;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        getloc = (Button) findViewById(R.id.getlocation);
        lati = (TextView) findViewById(R.id.latitude);
        longi = (TextView) findViewById(R.id.longitude);
        address = (TextView) findViewById(R.id.address);
        location_manager = (LocationManager)    getSystemService(Context.LOCATION_SERVICE);

        getloc.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {
        // TODO Auto-generated method stub
        LocationListener listner = new MyLocationListner();
        location_manager.requestLocationUpdates(
        LocationManager.GPS_PROVIDER, 0, 0, listner);

        }
        });

        }
    public class MyLocationListner implements LocationListener{


    private Address location;

    @TargetApi(Build.VERSION_CODES.GINGERBREAD)
    @SuppressWarnings("static-access")
    @Override
    public void onLocationChanged(Location arg0) {
        // TODO Auto-generated method stub
        getLatitude = "" + loc.getLatitude();
        getLongitude = "" + loc.getLongitude();

        lati.setText(getLatitude);
        longi.setText(getLongitude);

        x = location.getLatitude();
        y = location.getLongitude();

        try {
        geocoder = new Geocoder(MainActivity.this, Locale.ENGLISH);
        addresses = geocoder.getFromLocation(x, y, 1);
        StringBuilder str = new StringBuilder();
        if (geocoder.isPresent()) {
        Toast.makeText(getApplicationContext(),
        "geocoder present", Toast.LENGTH_SHORT).show();
        Address returnAddress = addresses.get(0);

        String localityString = returnAddress.getLocality();
        String city = returnAddress.getCountryName();
        String region_code = returnAddress.getCountryCode();
        String zipcode = returnAddress.getPostalCode();

        str.append(localityString + "");
        str.append(city + "" + region_code + "");
        str.append(zipcode + "");

        address.setText(str);
        Toast.makeText(getApplicationContext(), str,
        Toast.LENGTH_SHORT).show();

        } else {
        Toast.makeText(getApplicationContext(),
        "geocoder not present", Toast.LENGTH_SHORT).show();
        }

        // } else {
        // Toast.makeText(getApplicationContext(),
        // "address not available", Toast.LENGTH_SHORT).show();
        // }
        } catch (IOException e) {
        // TODO Auto-generated catch block

        Log.e("tag", e.getMessage());
        }

    }

    @Override
    public void onProviderDisabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
        // TODO Auto-generated method stub

    }

}
}

Answer 1

你正在使用 loc 并且没有对它做任何事情，它是空的

在你的里面

@Override
public void onLocationChanged(Location arg0) {
    // TODO Auto-generated method stub
    getLatitude = "" + loc.getLatitude();
    getLongitude = "" + loc.getLongitude();
///etc..........
}

你应该使用 arg0

getLatitude = "" + arg0.getLatitude();
    getLongitude = "" + arg0.getLongitude();

编辑:它实际上看起来与

相同

x = location.getLatitude();
        y = location.getLongitude();