i don't know how to show the button.

i am using org.osmdroid:osmdroid-android:6.1.8 and making android app include map. after i place mapview and button in layout.xml, i can't find button. what is problem and how can i solve this problem?

here layout.xml

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

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_marginTop="10dp"
    android:layout_marginRight="10dp"
    android:text="Select"
    />

<org.osmdroid.views.MapView
    android:id="@+id/locationMap"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

</relativelayout>

here is java code package com.example.copsys.OSM;

import android.app.Activity; import android.content.Context; import android.content.Intent; import android.graphics.Canvas; import android.graphics.drawable.Drawable; import android.os.Bundle; import android.os.PersistableBundle; import android.preference.PreferenceManager; import android.util.Log; import android.view.MotionEvent; import android.view.View; import android.widget.Toast;

import androidx.annotation.Nullable; import androidx.appcompat.app.AppCompatActivity;

import com.example.copsys.R;

import org.osmdroid.api.IMapController; import org.osmdroid.config.Configuration; import org.osmdroid.events.MapEventsReceiver; import org.osmdroid.tileprovider.tilesource.XYTileSource; import org.osmdroid.util.GeoPoint; import org.osmdroid.views.MapView; import org.osmdroid.views.Projection; import org.osmdroid.views.overlay.ItemizedIconOverlay; import org.osmdroid.views.overlay.ItemizedOverlayWithFocus; import org.osmdroid.views.overlay.MapEventsOverlay; import org.osmdroid.views.overlay.Overlay; import org.osmdroid.views.overlay.OverlayItem;

import java.util.ArrayList;

public class LocationMap extends AppCompatActivity {

private final String TAG = "LocationMap";

MapView map = null;
XYTileSource tileSource_4uMaps;
ArrayList<OverlayItem> items;
OverlayItem here = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getSupportActionBar().hide();
    //handle permissions first, before map is created. not depicted here
    //load/initialize the osmdroid configuration, this can be done
    Context ctx = getApplicationContext();
    Configuration.getInstance().load(ctx, PreferenceManager.getDefaultSharedPreferences(ctx));
    //setting this before the layout is inflated is a good idea
    //it 'should' ensure that the map has a writable location for the map cache, even without permissions
    //if no tiles are displayed, you can try overriding the cache path using Configuration.getInstance().setCachePath
    //see also StorageUtils
    //note, the load method also sets the HTTP User Agent to your application's package name, abusing osm's tile servers will get you banned based on this string
    //inflate and create the map
    setContentView(R.layout.osm_layout);

    map = (MapView)findViewById(R.id.map);
    tileSource_4uMaps = new XYTileSource("4uMaps", 8, 15, 256, ".png", new String[] {});

// tileSource_google = new XYTileSource("Google Maps Earth Kor", 8, 19, 256, ".png", new String[] {}); map.setTileSource(tileSource_4uMaps); map.setUseDataConnection(false); //optional, but a good way to prevent loading from the network and test your zip loading. map.setBuiltInZoomControls(true); map.setMultiTouchControls(true);

    IMapController mapController = map.getController();
    mapController.setZoom(15);
    GeoPoint startPoint = new GeoPoint( 35.86666, 128.600);
    mapController.setCenter(startPoint);

// //your items items = new ArrayList<overlayitem>(); here = null; // items.add(new OverlayItem("Title", "Description", startPoint)); // Lat/Lon decimal degrees // // //the overlay // ItemizedOverlayWithFocus<overlayitem> mOverlay = new ItemizedOverlayWithFocus<overlayitem>(items, // new ItemizedIconOverlay.OnItemGestureListener<overlayitem>() { // @Override // public boolean onItemSingleTapUp(final int index, final OverlayItem item) { // //do something //// map.setTileSource(tileSource_4uMaps); // return true; // } // @Override // public boolean onItemLongPress(final int index, final OverlayItem item) { //// map.setTileSource(tileSource_google); // return false; // } // }, getApplicationContext()); // mOverlay.setFocusItemsOnTap(true); // map.getOverlays().add(mOverlay); MapEventsReceiver mReceive = new MapEventsReceiver() { @Override public boolean singleTapConfirmedHelper(GeoPoint p) { Toast.makeText(getBaseContext(),p.getLatitude() + " - "+p.getLongitude(),Toast.LENGTH_LONG).show();

            here = new OverlayItem("Here", "select", p);
            items.add(here);
                    //the overlay
            ItemizedOverlayWithFocus<OverlayItem> mOverlay = new ItemizedOverlayWithFocus<OverlayItem>(items,
                    new ItemizedIconOverlay.OnItemGestureListener<OverlayItem>() {
                        @Override
                        public boolean onItemSingleTapUp(final int index, final OverlayItem item) {
                            //do something
    //                        map.setTileSource(tileSource_4uMaps);
                            return true;
                        }
                        @Override
                        public boolean onItemLongPress(final int index, final OverlayItem item) {
    //                        map.setTileSource(tileSource_google);
                            return false;
                        }
                    }, getApplicationContext());
            mOverlay.setFocusItemsOnTap(true);
            map.getOverlays().add(mOverlay);

            Intent i = new Intent();
            i.putExtra("lon", p.getLongitude());
            i.putExtra("lat", p.getLatitude());
            setResult(RESULT_OK, i);
            finish();

            return false;
        }

        @Override
        public boolean longPressHelper(GeoPoint p) {
            return false;
        }
    };


    MapEventsOverlay OverlayEvents = new MapEventsOverlay(getBaseContext(), mReceive);
    map.getOverlays().add(OverlayEvents);


}

public void onResume(){
    super.onResume();
    //this will refresh the osmdroid configuration on resuming.
    //if you make changes to the configuration, use
    //SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
    //Configuration.getInstance().load(this, PreferenceManager.getDefaultSharedPreferences(this));
    map.onResume(); //needed for compass, my location overlays, v6.0.0 and up
}

public void onPause(){
    super.onPause();
    //this will refresh the osmdroid configuration on resuming.
    //if you make changes to the configuration, use
    //SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
    //Configuration.getInstance().save(this, prefs);
    map.onPause();  //needed for compass, my location overlays, v6.0.0 and up
}

}