Error while using "findViewById" for mapview

Question

I have created a simple map application using OSM. Everything is working fine, but there is a problem when I am tring to use findViewById to denote the map in the layout.

I am getting this error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.openstreetmaptutorial/com.example.openstreetmaptutorial.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

The code of the activity:

public class MainActivity extends Activity {
double myCurrentLatitude;
    double myCurrentLongitude;

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

        //get current location
        GPSTracker tracker = new GPSTracker(this);
        if (tracker.canGetLocation() == false) {
            tracker.showSettingsAlert();
        } else {
            myCurrentLatitude = tracker.getLatitude();
            myCurrentLongitude = tracker.getLongitude();
        }

        MapView mapView = (MapView) findViewById(R.id.mapview);
        mapView.setClickable(true);
        mapView.setBuiltInZoomControls(true);
        mapView.setTileSource(TileSourceFactory.MAPQUESTOSM);
        mapView.getController().setZoom(15);
        mapView.getController().setCenter(new GeoPoint(myCurrentLatitude, myCurrentLongitude));

        List<Overlay> mapOverlays = mapView.getOverlays();
        Drawable drawable = this.getResources().getDrawable(R.drawable.pin_for_map);


        MapItemizedOverlay itemizedoverlay = new MapItemizedOverlay(drawable,this);
        itemizedoverlay.setEnabled(true);

        //setting pin to my current position on the map

        GeoPoint homePoint = new GeoPoint(myCurrentLatitude,myCurrentLongitude);
        OverlayItem overlayitem = new OverlayItem("Home Sweet Home", "name", homePoint);

        mapView.getController().setZoom(15);
        mapView.getController().setCenter(homePoint);

        itemizedoverlay.addOverlay(overlayitem);
        mapOverlays.add(itemizedoverlay);

        setContentView(mapView);

    }
}

The Layout file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

        <org.osmdroid.views.MapView
            android:id="@+id/mapview"
            android:layout_width="match_parent" 
            android:layout_height="match_parent"
            android:enabled="true"      
            android:clickable="true"
        />  


</RelativeLayout>

The line which is actually causing the error is:

MapView mapView = (MapView) findViewById(R.id.mapview);

If I change the line to:

MapView mapView = new MapView(this, 256);

Then there is no error. But I need to implement the former one, as I want to add some more controls to the layout via xml. What should I do to overcome the problem? Ho can I use findViewById without the specified error?

Answer 1

The problem is occurring when you are calling setContentView() method for the second time by passing mapView

setContentView(mapView);

The mapView belongs to its parent RelativeLayout. So, you are trying to set this mapView as activity layout ignoring its parents RelativeLayout then you are getting the IllegalStateException...

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.openstreetmaptutorial/com.example.openstreetmaptutorial.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

You can solve the problem by removing second setContentView() method call.

Answer 2

add this

MapView mapView = (MapView) findViewById(R.id.mapview);

and remove

setContentView(mapView);

from your code