GPS location won't display on phone

Issue

I'm trying to get the location from the GPS and display it on the screen, so far I have this code :

public class MainActivity extends AppCompatActivity implements LocationListener {

    EditText el;
    TextView output;

    LocationManager lm;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        el = (EditText) findViewById(R.id.editText);
        output = (TextView) findViewById(R.id.textView2);
        output.setMovementMethod(new ScrollingMovementMethod());
        output.setText("");

        LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        output.append("Start");
        if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

            //ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION}, 1);

             output.append("Initially Failed to Grand Permission\n");
             return;
        }
        output.append("\nOutside Permission controle");

        locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);
        output.append("\nYoo");

    }

    public void send(View v) {
        MessageSender messageSender = new MessageSender();
        messageSender.execute(el.getText().toString());
        output.append("Hello\n");

    }


    @Override
    public void onLocationChanged(@NonNull Location location) {
        output.append("Inside location function");
        output.append(String.valueOf(location.getLongitude()));
    }
}

I have also added permissions for fine location and coarse location in the android manifest. What am I missing?

I'm using Samsung galaxy S10

Note When I use the emulator on android studio, it shows the location, but when I use the usb debugger, and run it on my android device, it doesn't show the location

Also Even when I run it on the emulator, the location doesn't update when I move my laptop, why?

Solution

locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);

causes an error if you have not allowed ACCESS_FINE_LOCATION and ACCESS_COARSE_LOCATION so you have to ask those permissions. You can do that like this:

if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED ||
            ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION, Manifest.permission.ACCESS_FINE_LOCATION}, 1);
    } else {
        lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);
    }

Notice that && has changed to ||. Basically this code asks permissions if they have not been granted. If permissions have been granted, call the locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);

What if permissions have not been granted? You need to wait until permissions have been granted before you can call requestLocationUpdates. This method get called after permissions have been granted.

@Override
public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
    switch (requestCode) {
        case 1: {
            // If request is cancelled, the result arrays are empty.
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
                if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                    return;
                }
            locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10, 1, this);
            return;
        }
    }
}

Add this method into the activity. I tested this code with a physical device and it seems to work as it should.

Answered By - Matias Lappalainen