如何从导航抽屉中调用 Fragment Activity

Question

我想在第一种情况下显示地图，这是调用地图片段时 DrawerLayout 的一部分。这让我犯了错误，我不知道该怎么做。

@Override
    public void onNavigationDrawerItemSelected(int position) {

        FragmentManager fragmentManager = getFragmentManager();
        Fragment fragment =null;
        switch (position){
            case 0:
                fragment = new MapsActivity(); //this line show error
                break;
            
            case 1:
                //to implement
                break;
            case 2:
                //to implement
                break;
        }

        fragmentManager.beginTransaction()
                .replace(R.id.container, fragment)
                .commit();
    }

这是谷歌地图活动的代码：

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);
        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }


    @Override
    public void onMapReady(GoogleMap map) {

        LatLng minorca = new LatLng(40.001568, 3.837685);
        map.addMarker(new MarkerOptions().position(minorca).title("Minorca"));
        map.moveCamera(CameraUpdateFactory.newLatLng(minorca));
    }
}

我希望你能帮助我。谢谢！

Answer 1

那是因为navigation drawer需要用到fragment，但是你使用了activity，导致报错。

解决方案是您需要扩展Fragment，您需要将您的MapsActivity 更改为MapsFragment，如下所示：

public class MapsFragment extends Fragment {


    private MapView mapView;

    public static MapsFragment newInstance() {
        MapsFragment fragment = new MapsFragment();
        return fragment;
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.mapview, container, false);
        // Gets the MapView from the XML layout and creates it

        MapsInitializer.initialize(getActivity());


        switch (GooglePlayServicesUtil.isGooglePlayServicesAvailable(getActivity())) {
            case ConnectionResult.SUCCESS:
                Toast.makeText(getActivity(), "SUCCESS", Toast.LENGTH_SHORT).show();
                mapView = (MapView) v.findViewById(R.id.map);
                mapView.onCreate(savedInstanceState);
                // Gets to GoogleMap from the MapView and does initialization stuff
                if (mapView != null) {
                     mapView.getMapAsync(new OnMapReadyCallback() {
                        @Override
                        public void onMapReady(GoogleMap googleMap) {
                            googleMap.getUiSettings().setMyLocationButtonEnabled(true);
                            googleMap.setMyLocationEnabled(true);
                            CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(new LatLng(43.1, -87.9), 10);
                            googleMap.animateCamera(cameraUpdate);
                        }
                    });

                }
                break;
            case ConnectionResult.SERVICE_MISSING:
                Toast.makeText(getActivity(), "SERVICE MISSING", Toast.LENGTH_SHORT).show();
                break;
            case ConnectionResult.SERVICE_VERSION_UPDATE_REQUIRED:
                Toast.makeText(getActivity(), "UPDATE REQUIRED", Toast.LENGTH_SHORT).show();
                break;
            default:
                Toast.makeText(getActivity(), GooglePlayServicesUtil.isGooglePlayServicesAvailable(getActivity()), Toast.LENGTH_SHORT).show();
        }

        return v;
    }

    @Override
    public void onResume() {
        mapView.onResume();
        super.onResume();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mapView.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        mapView.onLowMemory();
    }
}

而布局xml文件为：

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

    <com.google.android.gms.maps.MapView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:name=".MapsFragment"/>

</RelativeLayout>

请注意，您应该在DrawerLayout 文件和MapsFragment 上都使用import android.support.v4.app.Fragment;。

终于用上了

fragment = MapsFragment.newInstance();

而不是

fragment = new MapsActivity(); //this line show error

在您的DrawerLayout。