MainActivity.java

package beuth.beuthmap;

import android.content.pm.PackageManager;
import android.os.Bundle;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.FragmentActivity;
import android.view.View;
import android.widget.Button;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
import com.google.maps.android.geojson.GeoJsonLayer;

import org.json.JSONException;

import java.io.IOException;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        // Obtain the SupportMapFragment and get notified when the map is ready to be used.
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);


        Button but0 = (Button) findViewById(R.id.button0);
        Button but1 = (Button) findViewById(R.id.button1);


        but0.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                GeoJsonLayer layer0 = null;

                try {
                    layer0 = new GeoJsonLayer(mMap, R.raw.level0,
                            getApplicationContext());
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (JSONException e) {
                    e.printStackTrace();
                }

                assert layer0 != null;
                layer0.addLayerToMap();

            }
        });

        but1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View arg0) {
                GeoJsonLayer layer1 = null;

                try {
                    layer1 = new GeoJsonLayer(mMap, R.raw.level1,
                            getApplicationContext());
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (JSONException e) {
                    e.printStackTrace();
                }

                assert layer1 != null;
                layer1.addLayerToMap();

            }
        });

        };



    /**
     * Manipulates the map once available.
     * This callback is triggered when the map is ready to be used.
     * This is where we can add markers or lines, add listeners or move the camera. In this case,
     * we just add a marker near Sydney, Australia.
     * If Google Play services is not installed on the device, the user will be prompted to install
     * it inside the SupportMapFragment. This method will only be triggered once the user has
     * installed Google Play services and returned to the app.
     */
    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        // Add a marker in Sydney and move the camera
        LatLng beuth = new LatLng(52.544307, 13.352703);
        mMap.addMarker(new MarkerOptions().position(beuth).title("Beuth Hochschule für Technik Berlin"));
        mMap.moveCamera(CameraUpdateFactory.newLatLng(beuth));
        mMap.animateCamera(CameraUpdateFactory.zoomTo(16));
        if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
            //    ActivityCompat#requestPermissions
            // here to request the missing permissions, and then overriding
            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
            //                                          int[] grantResults)
            // to handle the case where the user grants the permission. See the documentation
            // for ActivityCompat#requestPermissions for more details.
            return;
        }
        mMap.setMyLocationEnabled(true);
    }

}