獲取GPS位置

Question

我試圖獲取位置管理文本視圖裏面customDialog如下：

但給了我在java空指針異常

當我打開對話框，並得到GPS的工作它工作正常，但是當關閉對話框和GPS得到它的它越來越NPE位置。

注：我已編輯的代碼你

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_tjamo3_last_date); 

     locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
     locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this); 

     addNewPoint.setOnClickListener(new OnClickListener() { 

        @Override 
        public void onClick(View v) { 

         final Dialog dialog = new Dialog(Tjamo3LastDate.this); 

         dialog.setContentView(R.layout.custom_dialog); 
         dialog.setTitle("اضافة نقطة فحص جديدة"); 

         Button save =(Button)dialog.findViewById(R.id.save); 
         if (locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)){ 
          txtLat = (TextView) dialog.findViewById(R.id.textView1); 
          txtLag = (TextView) dialog.findViewById(R.id.textView2); 
          txtLat.setText("0.0"); 
          txtLag.setText("0.0"); 
         } 
         dialog.show(); 
         save.setOnClickListener(new OnClickListener() { 

          @Override 
          public void onClick(View v) { 
           EditText editText=(EditText)dialog.findViewById(R.id.editText); 
           txtLat = (TextView) dialog.findViewById(R.id.textView1); 
           txtLag = (TextView) dialog.findViewById(R.id.textView2); 
           txtLat.setText(String.valueOf(mm)); 
           txtLag.setText(String.valueOf(hh)); 

    }); 

    } 

    @Override 
    public void onLocationChanged(Location location) { 
     hh = location.getLatitude(); 
     mm = location.getLongitude(); 
    } 

Answer 1

public class GPSTracker extends Service implements LocationListener { 

private final 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 

// Declaring a Location Manager 
protected LocationManager locationManager; 

public GPSTracker(Context context) { 
    this.mContext = context; 
    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) { 
       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 void onLocationChanged(Location location) { 
} 

@Override 
public void onProviderDisabled(String provider) { 
} 

@Override 
public void onProviderEnabled(String provider) { 
} 

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

@Override 
public IBinder onBind(Intent arg0) { 
    return null; 
} 

} 

使用此服務，以獲得最新的位置。啓動該服務時，您的應用程序啓動

static GPSTracker gps; // set as your class variable to access anywhere from app 
gps = new GPSTracker(getApplicationContext()); 

後，您可以使用

txtLat.setText(MainActivity.gps.getLatitude().toString()); 

一樣在對話框經度。

請註明有權這個答案是否對你有幫助。

Answer 2

根據我們聊天：

保持到txtLat和txtLang並在對話框把參考這個

if(location!=null){ 
    txtLat.setText("" + location.getLatitude()); 
    txtLag.setText("" + location.getLongitude()); 
} 

然後用這個

@Override 
public void onLocationChanged(Location loc) { 
    location = loc; 
    if(txtLat !=null && txtLag!=null){ 
    txtLat.setText("" + location.getLatitude()); 
    txtLag.setText("" + location.getLongitude()); 
}