android - 计时器和 map Android

Question

我在 map 上显示 ItemizedOverlay(s) 时遇到了一些问题。在这里，我提取了一个我需要做的简化示例。这是我的 map 类:

import java.util.Timer;
import java.util.TimerTask;

import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.util.Log;

import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;
import com.google.android.maps.OverlayItem;

public class Map extends MapActivity {
protected static final String TAG = "Map";
private int test = 0;
private TestItemized items = null;
private Timer timer = new Timer();
private MapView map = null;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    this.map = (MapView) this.findViewById(R.id.myMapView1);
    this.map.setBuiltInZoomControls(true);
    this.map.setSatellite(false);
    this.map.setStreetView(true);
    this.map.setClickable(true);
    this.timer.scheduleAtFixedRate(new TimerTask(){

        @Override
        public void run() {
            Log.d(TAG, "refeshing: "+ String.valueOf(test));
            Drawable drawable = Map.this.getResources().getDrawable(R.drawable.androidmarker);
            test++;
            if (Map.this.items instanceof TestItemized && Map.this.map.getOverlays().contains(Map.this.items))
                Map.this.map.getOverlays().remove(Map.this.items);
            //some code might go here to retrieve new coordinates but this isn't a problem
            Map.this.items = new TestItemized(drawable, Map.this);
            double lat = 46.491734;
            Log.d(TAG,"Latitude : "+ String.valueOf(lat));
            double lng = 11.320365;
            Log.d(TAG,"Longitude : "+ String.valueOf(lng));

            OverlayItem item = new OverlayItem(new GeoPoint((int)(lat * 1E6), (int)(lng * 1E6)), String.valueOf(Map.this.test), "blah!");
            Map.this.items.addOverlay(item);
            Map.this.map.getOverlays().add(Map.this.items);
            Log.d(TAG,"refreshing "+String.valueOf(test)+" is over");
            }}, 1000,60000);        

}

@Override
protected boolean isRouteDisplayed() {
    return false;
}
}

我按照谷歌提供的指南扩展了 ItemizedOverlay 类

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.graphics.drawable.Drawable;
import android.widget.Toast;

import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.OverlayItem;


@SuppressWarnings("rawtypes")
public class TestItemized extends ItemizedOverlay {
private Context mCtx;
private List<OverlayItem> mItems = new ArrayList<OverlayItem>();

public TestItemized(Drawable arg0) {
    super(arg0);
}

/**
 * @param defaultMarker
 * @param mCtx
 */
public TestItemized(Drawable defaultMarker, Context mCtx) {
    super(defaultMarker);
    this.mCtx = mCtx;
}

public void addOverlay(OverlayItem overlay) {
    this.mItems.add(overlay);
    populate();
}


@Override
protected OverlayItem createItem(int i) {
    return this.mItems.get(i);
}

@Override
public int size() {
    return mItems.size();
}

/* (non-Javadoc)
 * @see com.google.android.maps.ItemizedOverlay#onTap(int)
 */
@Override
protected boolean onTap(int index) {
    OverlayItem item = this.mItems.get(index);
    Toast.makeText(this.mCtx, item.getTitle() +" : " +item.getSnippet(), Toast.LENGTH_LONG).show();
    return true;

}


} 

从代码中可以清楚地看出，我需要在固定时间更新 map UI，可能会有新的位置，所以我使用的是计时器，但我认为我可能会陷入某种我不会遇到的线程问题知道如何处理，因为在运行测试时我可以在日志中看到发生了什么，但 map 上没有绘制标记。有谁知道如何解决这类问题？

Answer 1

在 run() 方法结束时，完成更新 MapView 后，您应该调用

Map.this.map.postInvalidate();