Question

i develop an app to retrieve current location via GPS but it return null i want my app use gps only not 3g or wifi i used bestprovider but it retrieve only when i run it and not always work

this is the java code :

    package com.example.loc2;

    import android.location.Location;
 import android.location.LocationListener;
   import android.location.LocationManager;
  import android.os.Bundle;
   import android.app.Activity;
   import android.content.Context;
   import android.view.Menu;
    import android.view.View;
  import android.view.View.OnClickListener;
  import android.widget.Button;
   import android.widget.Toast;

   public class MainActivity extends Activity {
private static final long MINIMUM_DISTANCE_CHANGE_FOR_UPDATES = 1; // in Meters  
private static final long MINIMUM_TIME_BETWEEN_UPDATES = 1000; // in Milliseconds
protected LocationManager locationManager;
protected Button retrieveLocationButton;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    retrieveLocationButton = (Button) findViewById(R.id.retrieve_location_button);

    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

    locationManager.requestLocationUpdates(
            LocationManager.GPS_PROVIDER, 
            MINIMUM_TIME_BETWEEN_UPDATES, 
            MINIMUM_DISTANCE_CHANGE_FOR_UPDATES,
            new MyLocationListener()
    );

retrieveLocationButton.setOnClickListener(new OnClickListener() {
       // @Override
        public void onClick(View v) {
            showCurrentLocation();
        }
});        

}    

protected void showCurrentLocation() {

    Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

    if (location != null) {
        String message = String.format(
                "Current Location \n Longitude: "+location.getLongitude()+" \n Latitude:"+
                 location.getLatitude());

        Toast.makeText(  MainActivity.this,message,
                Toast.LENGTH_LONG).show();
    }

}   

private class MyLocationListener implements LocationListener {

    public void onLocationChanged(Location location) {
        String message = String.format(
                "New Location \n Longitude: %1$s \n Latitude: %2$s",
                location.getLongitude(), location.getLatitude()
        );
        Toast.makeText(MainActivity.this, message, Toast.LENGTH_LONG).show();
    }

    public void onStatusChanged(String s, int i, Bundle b) {
        Toast.makeText(MainActivity.this, "Provider status changed",
                Toast.LENGTH_LONG).show();
    }

    public void onProviderDisabled(String s) {
        Toast.makeText(MainActivity.this,
                "Provider disabled by the user. GPS turned off",
                Toast.LENGTH_LONG).show();
    }

    public void onProviderEnabled(String s) {
        Toast.makeText(MainActivity.this,
                "Provider enabled by the user. GPS turned on",
                Toast.LENGTH_LONG).show();
    }

}

}

and this is the manifest:
i used this permission

  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.loc2"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="15" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION"/>

<application
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/title_activity_main" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    </application>

    </manifest>

please help

Answer 1

Look at this, it will help you

 LocationManager mlocManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    LocationListener mlocListener = new MyLocationListener();
mlocManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0,
            mlocListener);

public class MyLocationListener implements LocationListener {

    @Override
    public void onLocationChanged(Location loc) {
        loc.getLatitude();
        loc.getLongitude();

        Geocoder gcd = new Geocoder(getApplicationContext(),
                Locale.getDefault());
        try {
            mAddresses = gcd.getFromLocation(loc.getLatitude(),
                    loc.getLongitude(), 1);

        } catch (IOException e) {

        }

        String cityName = (mAddresses != null) ? mAddresses.get(0)
                .getLocality() : TimeZone.getDefault().getID();
        String countryName = (mAddresses != null) ? mAddresses.get(0)
                .getCountryName() : Locale.getDefault().getDisplayCountry()
                .toString();


        mCurrentSpeed.setText("Longitude"+loc.getLongitude()+" Latitude"+loc.getLatitude());
    }

    @Override
    public void onProviderDisabled(String provider) {
        Toast.makeText(getApplicationContext(), "Gps Disabled",
                Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onProviderEnabled(String provider) {
        Toast.makeText(getApplicationContext(), "Gps Enabled",
                Toast.LENGTH_SHORT).show();
    }

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