Why am i getting " java.lang.NullPointerException" in my android app?

Question

I want to show "hello" message on the screen but my app is not working.

What is causing "java.lang.NullPointerException"?

the debugger says value of longitude is null. Even if that is the case, shouldn’t my "hello" message still appear?

I have the following code:

 package autogenie.maptrial;

 import android.Manifest;

 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.location.Location;
 import android.location.LocationManager;
 import android.support.v4.app.ActivityCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
private Location location;
private Double latitude, longitude;
private LocationManager locationManager;


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

    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;
    }


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

    location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

    longitude=location.getLongitude();
    latitude=location.getLatitude();



    Context context = getApplicationContext();
    String s="hello";
    int duration = Toast.LENGTH_LONG;

    Toast toast = Toast.makeText(context,s, duration);
    toast.show();


}
}

What debugger shows:

After that it crashes.

Please add the stacktrace of the error (the stuff you see in the debugger) — Kelevandos, Jan 15 '16 at 13:14

score 2 · Accepted Answer · answered Jan 15 '16 at 13:25

Replace

longitude=location.getLongitude();
latitude=location.getLatitude();

with

if( location != null ) {
    longitude=location.getLongitude();
    latitude=location.getLatitude();
}

It is not longitude field that is null, but the location field, on which you are trying to invoke a method call. This produces the exception. When you replace the code as noted above, you will get the program to work without a crash.

score 0 · Answer 2 · answered Jan 15 '16 at 13:20

0

Please check if GPS_Provider is enabled. It looks like GPS is not enabled and you try to use that. location will be null in that case

answered Jan 15 '16 at 13:20

Mustansar Saeed

2,730
2
22
46

score 0 · Answer 3 · answered Jan 15 '16 at 13:25

0

add below check -

if(location != null){
    longitude=location.getLongitude();
    latitude=location.getLatitude();
}

answered Jan 15 '16 at 13:25

kevz

2,727
14
39

score 0 · Answer 4 · answered Jan 15 '16 at 13:28

0

Set a condition on location instance , if it is not null , only then proceed.

You should use FusedLocationProviderApi for getting the current location as per android documentation. Read more here : Getting the Last Known Location

answered Jan 15 '16 at 13:28

Tafveez Mehdi

456
3
12

Why am i getting " java.lang.NullPointerException" in my android app?

4 Answers4