Question

Hi dudes I am new to android I am getting null while creating location object using LocationManager.GPS_PROVIDER.

Here My GPSDemoActivity :

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

public class GPSDemoActivity extends Activity {

    private static final long MINIMUM_DISTANCE = 1;
    private static final long MINIMUM_TIME = 1000;

    protected LocationManager locationManager;

    // private Button showlocationButton;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // showlocationButton = (Button) findViewById(R.id.btn_showlocation);
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER,
                MINIMUM_DISTANCE, MINIMUM_TIME, new MyLocationListener());
    }

    public void showLocation(View v) {
        Toast.makeText(this, "Clicked", Toast.LENGTH_LONG).show();
        Location location = locationManager
                .getLastKnownLocation(LocationManager.GPS_PROVIDER);//here getting null.

        if (location != null) {
            String message = String.format(
                    "Current Location: \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude());
            Toast.makeText(this, message, Toast.LENGTH_LONG).show();
        }

    }

    private class MyLocationListener implements LocationListener {

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

        @Override
        public void onProviderDisabled(String provider) {

            Toast.makeText(GPSDemoActivity.this, "Provider disabled by the user. GPS turned off", Toast.LENGTH_LONG).show();

        }

        @Override
        public void onProviderEnabled(String provider) {

            Toast.makeText(GPSDemoActivity.this,
                    "Provider disabled by the user. GPS turned on",
                    Toast.LENGTH_LONG).show();

        }

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

            Toast.makeText(GPSDemoActivity.this,
                    "Provider status changed", Toast.LENGTH_LONG).show();


        }

    }
}

Here below My xml.
main.xml:

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

   <Button
       android:id="@+id/btn_showlocation" 
       android:layout_height="wrap_content"
       android:layout_width="wrap_content"
       android:text="@string/btn_showlocation"
       android:layout_gravity="center"
       android:onClick="showLocation"
       />

</LinearLayout>

here my manifest.xml.
My manifest.xml:

 <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.gps"
    android:versionCode="1"
    android:versionName="1.0" >

   <uses-sdk android:minSdkVersion="8" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".GPSDemoActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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


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

</manifest>

Answer 1

locationManager.getLastKnownLocation returns valid value only if you are able to detect location atleast once.

Are you sure location search using gps is enabled on your device, only then location manager can retreieve locations