How to access custom view from public void function in Android?

Question

I want to access custom view from public void onLocationChanged in public class MyCurrentLocationListener implements LocationListener. MyActivity:

public class MyActivity extends ActionBarActivity {
public final static String EXTRA_MESSAGE = "net.motameni.alisapp.MESSAGE";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    MyCurrentLocationListener locationListener = new MyCurrentLocationListener();
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, locationListener);
}

and MyCurrentLocationListener is this:

public class MyCurrentLocationListener implements LocationListener {

public void onLocationChanged(Location location) {
    TextView textView = (TextView) findViewById(R.id.location_message);
    textView.setTextSize(40);
    textView.setText("hello");
    setContentView(textView);
}

What is wrong???

Answer 1

You can not do UI changes from non UI function.

for doing this either you have to pass your view object to listener method, Or you have to create a method in your activity class that receive value from listener and updated value of your view.

update code in your oncreate:

TextView tv = (TextView)findViewById(R.id.tv1);
MyCurrentLocationListener locationListener = new MyCurrentLocationListener(tv);

and in your listener class create a constructor -

  TextView textView;
  public MyCurrentLocationListener (TextView  tv){
        textView = tv;
  }

and form location change -

public void onLocationChanged(Location location) {

 textView.setTextSize(40);
 textView.setText("hello");
}

this is the best way.