Change sublayer visibility

/* Copyright 2016 Esri
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.esri.arcgisruntime.sample.mapimagelayersublayervisibility;

import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;

import androidx.appcompat.app.AppCompatActivity;
import com.esri.arcgisruntime.layers.ArcGISMapImageLayer;
import com.esri.arcgisruntime.layers.SublayerList;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.Viewpoint;
import com.esri.arcgisruntime.mapping.view.MapView;

public class MainActivity extends AppCompatActivity {

  private MapView mMapView;
  private ArcGISMapImageLayer mMapImageLayer;
  private SublayerList mLayers;

  // The layer on/off menu items.
  private MenuItem mCities = null;
  private MenuItem mContinent = null;
  private MenuItem mWorld = null;

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

    // inflate MapView from layout
    mMapView = findViewById(R.id.mapView);
    // create a map with the Basemap Type topographic
    ArcGISMap map = new ArcGISMap();
    // create a MapImageLayer with dynamically generated map images
    mMapImageLayer = new ArcGISMapImageLayer(getResources().getString(R.string.world_cities_service));
    mMapImageLayer.setOpacity(0.9f);
    // add world cities layers as map operational layer
    map.getOperationalLayers().add(mMapImageLayer);
    // set the map to be displayed in this view
    mMapView.setMap(map);
    mMapView.setViewpoint(new Viewpoint(48.354406, -99.998267, 100000000.0));
    // get the layers from the map image layer
    mLayers = mMapImageLayer.getSublayers();

  }

  @Override
  protected void onPause() {
    super.onPause();
    mMapView.pause();
  }

  @Override
  protected void onResume() {
    super.onResume();
    mMapView.resume();
  }

  @Override
  protected void onDestroy() {
    super.onDestroy();
    mMapView.dispose();
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);

    // Get the sub layer switching menu items.
    mCities = menu.getItem(0);
    mContinent = menu.getItem(1);
    mWorld = menu.getItem(2);

    // set all layers on by default
    mCities.setChecked(true);
    mContinent.setChecked(true);
    mWorld.setChecked(true);

    return true;
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    // handle menu item selection
    //if-else is used because this sample is used elsewhere as a Library module
    int itemId = item.getItemId();
    if (itemId == R.id.Cities) {
      if (mLayers.get(0).isVisible() && mCities.isChecked()) {
        // cities layer is on and menu item checked
        mLayers.get(0).setVisible(false);
        mCities.setChecked(false);
      } else if (!mLayers.get(0).isVisible() && !mCities.isChecked()) {
        // cities layer is off and menu item unchecked
        mLayers.get(0).setVisible(true);
        Log.d("cities", String.valueOf(mLayers.get(0).getOpacity()));
        mCities.setChecked(true);
      }
      return true;
    } else if (itemId == R.id.Continents) {
      if (mLayers.get(1).isVisible() && mContinent.isChecked()) {
        // continent layer is on and menu item checked
        mLayers.get(1).setVisible(false);
        mContinent.setChecked(false);
      } else if (!mLayers.get(1).isVisible() && !mContinent.isChecked()) {
        // continent layer is off and menu item unchecked
        mLayers.get(1).setVisible(true);
        Log.d("continents", String.valueOf(mLayers.get(1).getOpacity()));
        mContinent.setChecked(true);
      }
      return true;
    } else if (itemId == R.id.World) {
      if (mLayers.get(2).isVisible() && mWorld.isChecked()) {
        // world layer is on and menu item checked
        mLayers.get(2).setVisible(false);
        mWorld.setChecked(false);
      } else if (!mLayers.get(2).isVisible() && !mWorld.isChecked()) {
        // world layer is off and menu item unchecked
        mLayers.get(2).setVisible(true);
        Log.d("world", String.valueOf(mLayers.get(2).getOpacity()));
        mWorld.setChecked(true);
      }
      return true;
    } else {
      return super.onOptionsItemSelected(item);
    }
  }

}