Toast 消息显示纬度和经度均为 0
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【中文标题】Toast 消息显示纬度和经度均为 0【英文标题】：Toast message shows 0 for both latitude and longitude 【发布时间】：2018-01-05 09:21:35 【问题描述】：我正在尝试从here 构建一个应用程序，用户单击button 并获取当前的纬度和经度，但问题是我得到0.0 的纬度和经度。我的应用程序中有一个activity 和一个service。 activity 和 service 的代码如下：
GpsActivity.java
public class GpsActivity extends AppCompatActivity
Button show;
private static final int REQUEST_CODE_PERMISSION = 2;
String mPermission = Manifest.permission.ACCESS_FINE_LOCATION;
GPSTracker gps;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_gps);
try
if (ActivityCompat.checkSelfPermission(this, mPermission)
!= PackageManager.PERMISSION_GRANTED)
ActivityCompat.requestPermissions(this, new String[]mPermission,
REQUEST_CODE_PERMISSION);
// If any permission above not allowed by user, this condition will
// execute every time, else your else part will work
catch (Exception e)
e.printStackTrace();
show=(Button)findViewById(R.id.showLocation);
show.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
gps=new GPSTracker(GpsActivity.this);
// check if GPS enabled
if(gps.canGetLocation())
double latitude = gps.getLatitude();
double longitude = gps.getLongitude();
// \n is for new line
Toast.makeText(getApplicationContext(), "Your Location is - \nLat: "
+ latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();
else
// can't get location
// GPS or Network is not enabled
// Ask user to enable GPS/network in settings
gps.showSettingsAlert();
);
GPSTracker.java
public class GPSTracker extends Service implements LocationListener
private Context mContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
// flag for GPS status
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute
protected LocationManager locationManager;
public GPSTracker()
//mContext = null;
public GPSTracker(Context mContext)
this.mContext = mContext;
getLocation();
public Location getLocation()
try
locationManager = (LocationManager) mContext.getSystemService(LOCATION_SERVICE);
// getting GPS status
isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isGPSEnabled && !isNetworkEnabled)
// no network provider is enabled
else
this.canGetLocation = true;
// First get location from Network Provider
if (isNetworkEnabled)
if (ActivityCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this,
Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)
// TODO: Consider calling
// ActivityCompat#requestPermissions
// here to request the missing permissions, and then overriding
// public void onRequestPermissionsResult(int requestCode, String[] permissions,
// int[] grantResults)
// to handle the case where the user grants the permission. See the documentation
// for ActivityCompat#requestPermissions for more details.
return location;
locationManager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("Network", "Network");
if (locationManager != null)
location = locationManager
.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
if (location != null)
latitude = location.getLatitude();
longitude = location.getLongitude();
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled)
if (location == null)
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
MIN_TIME_BW_UPDATES,
MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
Log.d("GPS Enabled", "GPS Enabled");
if (locationManager != null)
location = locationManager
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if (location != null)
latitude = location.getLatitude();
longitude = location.getLongitude();
catch (Exception e)
e.printStackTrace();
return location;
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS()
if(locationManager != null)
locationManager.removeUpdates(GPSTracker.this);
/**
* Function to get latitude
* */
public double getLatitude()
if(location != null)
latitude = location.getLatitude();
// return latitude
return latitude;
/**
* Function to get longitude
* */
public double getLongitude()
if(location != null)
longitude = location.getLongitude();
// return longitude
return longitude;
/**
* Function to check GPS/wifi enabled
* @return boolean
* */
public boolean canGetLocation()
return this.canGetLocation;
/**
* Function to show settings alert dialog
* On pressing Settings button will lauch Settings Options
* */
public void showSettingsAlert()
AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);
// Setting Dialog Title
alertDialog.setTitle("GPS is settings");
// Setting Dialog Message
alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");
// On pressing Settings button
alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener()
public void onClick(DialogInterface dialog,int which)
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
mContext.startActivity(intent);
);
// on pressing cancel button
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener()
public void onClick(DialogInterface dialog, int which)
dialog.cancel();
);
// Showing Alert Message
alertDialog.show();
@Override
public IBinder onBind(Intent intent)
// TODO: Return the communication channel to the service.
return null;
@Override
public void onLocationChanged(Location location)
@Override
public void onStatusChanged(String s, int i, Bundle bundle)
@Override
public void onProviderEnabled(String s)
@Override
public void onProviderDisabled(String s)
我已经在manifest 文件中提到了位置更新所需的所有permissions。这里唯一的问题是latitude 和longitude 在单击按钮时显示0.0。
有人可以帮忙吗？谢谢你:)
【问题讨论】：
你在安卓模拟器中运行应用吗？ 在真机上运行应用并开启gps 我已经这样做了，但它显示 0 GPSTracker.java 类是您代码中的一项服务，您不能像以前那样使用。您可以绑定服务并获取值。 您能否详细说明如何将service 绑定到我的activity
【参考方案1】：
你没有调用getLocation()方法
if(gps.canGetLocation())
gps.getLocation();
double latitude = gps.getLatitude();
double longitude = gps.getLongitude();
// \n is for new line
Toast.makeText(getApplicationContext(), "Your Location is - \nLat: "
+ latitude + "\nLong: " + longitude, Toast.LENGTH_LONG).show();
【讨论】：
完成，但仍为latitude 和 longitude 显示 0.0
检查你的 logcat 是否打印了异常
不，没有打印异常【参考方案2】：
函数getLastKnownLocation() 正在返回null。我建议等待一个新的位置在onLocationChanged() 中被调用并使用该位置对象。
另外，您没有正确使用Service 类。您基本上围绕LocationManager 创建了一个包装器。如果您想知道如何正确使用Service，请查看此tutorial。
【讨论】：
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