Question

我一直在玩GoogleMaps API并偶然发现这个错误，我试图在我的地图上使用CustomItemizedOverlay设置标记...当我尝试从我的项目资源访问我的一个图像时它返回null，甚至日食本身表示我试图使用的图像中的正确ID：/

关于我在这里做错了什么的线索？

PS：我已经搜索了很多关于这种错误的帖子，但到目前为止还没有人能够解决这个问题。

import java.util.List;
import android.content.res.Resources;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapController;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.OverlayItem;

   public class MapHandlerActivity extends MapActivity {


     private MapView mapView;
     private static final int latitudeE6 = 37985339;
     private static final int longitudeE6 = 23716735;

     //this is me trying to hardcode the image id to check 
     //if it will be found, didnt work
     public static final int android_tiny_image=0x7f020000;


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //setContentView(R.layout.main);
    setContentView(R.layout.maphandler);

    mapView = (MapView) findViewById(R.id.map_view);      
    mapView.setBuiltInZoomControls(true);

    List<Overlay> mapOverlays = mapView.getOverlays();

    //apparently returns my Resources just fine here
    Resources res = this.getResources();

    //this becomes null due to getDrawable returning null
    //Drawable drawable = this.getResources().getDrawable(android_tiny_image);
    (this is how i was originally trying to get my drawable, still returns null)Drawable drawable = this.getResources().getDrawable(R.drawable.android_tiny_image);
    CustomItemizedOverlay itemizedOverlay = new CustomItemizedOverlay(drawable, this);
    GeoPoint point = new GeoPoint(latitudeE6, longitudeE6);
    OverlayItem overlayItem = new OverlayItem(point, "Olá", "Estou em Athena, Grécia!");

    itemizedOverlay.addOverlay(overlayItem);
    mapOverlays.add(itemizedOverlay);

    MapController mapController = mapView.getController();

    mapController.animateTo(point);
    mapController.setZoom(6);
}
@Override
protected boolean isRouteDisplayed() {
    return true;
}

}

Answer 1

永远不要对资源ID进行硬编码。在对资源进行任何更改后，您可以随时更改项目。

Answer 2

正如其他人所提到的，资源ID可以更改，因此您应该使用R.drawable.image_name而不是 android_tiny_image 。但是，如果您确实需要资源标识符，则可以使用 public int getIdentifier（String name，String defType，String defPackage）从资源名称中提取资源标识符，该名称将返回给定资源名称的资源标识符像：

int android_tiny_image = getResources().getIdentifier("image_name", "drawable","your_package_name");

getResources（）。getDrawable返回NULL

2 个答案: