谷歌地图标记不'；t出现在Android Studio应用程序中

我已经实现了一个导航抽屉，它的菜单是片段。我把地图放在了主碎片中，它确实出现了，但标记没有。这里是应用程序中任何地方都不会显示的标记代码。 地图活动：

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

     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);
    }




    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;


        LatLng muze = new LatLng(41.326382, 19.821458);

        mMap.addMarker(new MarkerOptions().position(muze).title("National Museum of Tirana"));


        LatLng liqen = new LatLng(41.326382, 19.821458);

        mMap.addMarker(new MarkerOptions().position(liqen).title("Artifical Lake of Tirana"));



        LatLng monument = new LatLng(41.320155, 19.786377);

        mMap.addMarker(new MarkerOptions().position(monument).title("Skanderbeg STatue"));


        LatLng teater = new LatLng(41.321693, 19.817442);

        mMap.addMarker(new MarkerOptions().position(teater).title("National Theatre"));


        mMap.moveCamera(CameraUpdateFactory.newLatLng(muze));

        LatLng TiranaCenter = new LatLng(41.327541, 19.818609);
        mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(TiranaCenter,15.0f));


        mMap.setOnInfoWindowClickListener(new GoogleMap.OnInfoWindowClickListener() {
            @Override
            public void onInfoWindowClick(Marker m) {
                Intent intent1 = new Intent(getApplicationContext(),marker.class);
                String title = m.getTitle();

                intent1.putExtra("title",title);


                startActivity(intent1);
            }
        });
    }
}

marker.java

package com.example.user.appsightseeing;

/**
 * Created by User on 20/06/2017.
 */


import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.TextView;

import static com.example.user.appsightseeing.R.layout.activity_maps;

public class marker extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(activity_maps);

        String cinema_id =getIntent().getStringExtra("title");
        TextView text = (TextView)findViewById(R.id.emri);
        text.setText(cinema_id);

    }
}

---

看看代码中的这个函数

@Override
public void onMarkerDragEnd(Marker marker) {

    Toast.makeText(
            MainActivity.this,
            "Lat " + map.getMyLocation().getLatitude() + " "
                    + "Long " + map.getMyLocation().getLongitude(),
            Toast.LENGTH_LONG).show();
    System.out.println("yalla b2a "
            + map.getMyLocation().getLatitude());
}

---

看看代码中的这个函数…

OP的代码中没有这样的方法。