Question

我使用OSM创建了一个简单的地图应用程序。一切都运行正常，但是当我想使用 findViewById 来表示布局中的地图时，会出现问题。

我收到错误：

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.openstreetmaptutorial/com.example.openstreetmaptutorial.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

活动代码：

public class MainActivity extends Activity {
double myCurrentLatitude;
    double myCurrentLongitude;

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

        //get current location
        GPSTracker tracker = new GPSTracker(this);
        if (tracker.canGetLocation() == false) {
            tracker.showSettingsAlert();
        } else {
            myCurrentLatitude = tracker.getLatitude();
            myCurrentLongitude = tracker.getLongitude();
        }

        MapView mapView = (MapView) findViewById(R.id.mapview);
        mapView.setClickable(true);
        mapView.setBuiltInZoomControls(true);
        mapView.setTileSource(TileSourceFactory.MAPQUESTOSM);
        mapView.getController().setZoom(15);
        mapView.getController().setCenter(new GeoPoint(myCurrentLatitude, myCurrentLongitude));

        List<Overlay> mapOverlays = mapView.getOverlays();
        Drawable drawable = this.getResources().getDrawable(R.drawable.pin_for_map);


        MapItemizedOverlay itemizedoverlay = new MapItemizedOverlay(drawable,this);
        itemizedoverlay.setEnabled(true);

        //setting pin to my current position on the map

        GeoPoint homePoint = new GeoPoint(myCurrentLatitude,myCurrentLongitude);
        OverlayItem overlayitem = new OverlayItem("Home Sweet Home", "name", homePoint);

        mapView.getController().setZoom(15);
        mapView.getController().setCenter(homePoint);

        itemizedoverlay.addOverlay(overlayitem);
        mapOverlays.add(itemizedoverlay);

        setContentView(mapView);

    }
}

布局文件：

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

        <org.osmdroid.views.MapView
            android:id="@+id/mapview"
            android:layout_width="match_parent" 
            android:layout_height="match_parent"
            android:enabled="true"      
            android:clickable="true"
        />  


</RelativeLayout>

实际导致错误的行是：

MapView mapView =（MapView）findViewById（R.id.mapview）;

如果我将该行更改为：

MapView mapView = new MapView（this，256）;

然后没有错误。但我需要实现前者，因为我想通过xml为布局添加更多控件。我该怎么做才能克服这个问题？我可以在没有指定错误的情况下使用 findViewById 吗？

Answer 1

通过传递setContentView()

第二次调用mapView方法时出现问题

setContentView(mapView);

mapView属于其父RelativeLayout。因此，您尝试将此mapView设置为活动布局而忽略其父级RelativeLayout，然后您将获得IllegalStateException ...

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.openstreetmaptutorial/com.example.openstreetmaptutorial.MainActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

您可以通过删除第二个setContentView()方法调用来解决问题。

Answer 2

添加此

MapView mapView = (MapView) findViewById(R.id.mapview);

并删除

setContentView(mapView);

来自您的代码

使用“findViewById”进行mapview时出错

2 个答案: