我该如何在谷歌地图视图中添加点，同时仍然允许用户与地图交互

Question

我有一个线程，它接收从服务器发送的映射点，并将这些点添加到MapView中。这很好，但如果我与MapView交互（例如放大、平移等），我会得到一个ConcurrentModificationException，那么我如何在向MapView添加点的同时允许访问用户？

02-20 01:44:26.566: E/AndroidRuntime(9448):     FATAL EXCEPTION: main
02-20 01:44:26.566: E/AndroidRuntime(9448):     java.util.ConcurrentModificationException
02-20 01:44:26.566: E/AndroidRuntime(9448):     at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:569)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at com.google.android.maps.OverlayBundle.draw(OverlayBundle.java:41)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at com.google.android.maps.MapView.onDraw(MapView.java:532)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.View.draw(View.java:13707)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.View.draw(View.java:13591)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.View.draw(View.java:13589)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.View.draw(View.java:13589)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.View.draw(View.java:13589)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.drawChild(ViewGroup.java:2928)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2797)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.View.draw(View.java:13710)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.widget.FrameLayout.draw(FrameLayout.java:467)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:2211)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewRootImpl.drawSoftware(ViewRootImpl.java:2281)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewRootImpl.draw(ViewRootImpl.java:2177)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewRootImpl.performDraw(ViewRootImpl.java:2045)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1854)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.Choreographer.doCallbacks(Choreographer.java:562)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.Choreographer.doFrame(Choreographer.java:532)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.os.Handler.handleCallback(Handler.java:725)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.os.Handler.dispatchMessage(Handler.java:92)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.os.Looper.loop(Looper.java:137)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at android.app.ActivityThread.main(ActivityThread.java:5039)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at java.lang.reflect.Method.invokeNative(Native Method)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at java.lang.reflect.Method.invoke(Method.java:511)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
02-20 01:44:26.566: E/AndroidRuntime(9448):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

您尝试过使用新的maps-api吗？就我个人而言，我发现它更容易使用，也更容易从旧的API更改为新的API。

链接：https://developers.google.com/maps/documentation/android/

我发现有一件事特别改进，那就是地图上的绘图。再也不用处理大量溢出等问题了。使用新API添加引脚的示例是：

    final GoogleMap map = this.getMap();
    final MarkerOptions marker = new MarkerOptions();
    marker.position(latlng);
    marker.draggable(false);
    marker.icon(BitmapDescriptorFactory.fromResource(drawable));
    map.addMarker(marker);

Answer 2

虽然在后台线程中从服务器接收点是合适的，但实际上应该在UI线程中添加/更新点。这样可以防止任何并发的修改问题。只要添加/更新过程不太繁重，就不会对用户体验产生重大干扰。

Answer 3

我已经尝试提取和清理一些使用旧api的旧代码。亮点包括：

1. 创建尚未在地图上的覆盖
2. 绘制和以其他方式准备覆盖层
3. 将覆盖添加到地图
4. 强制重新绘制地图

将此方法添加到您的活动

// check if overlay we are adding was already added
final List<Overlay> listOfOverlays = this.mMapView.getOverlays();
if ((this.mPinsOverlay != null) && listOfOverlays.contains(this.mPinsOverlay))
{
    listOfOverlays.remove(this.mPickupOverlay);
}
// create overlay
this.mPinsOverlay = new PinsOverlay();
// add overlay to map
listOfOverlays.add(this.mPinsOverlay);
// force map to redraw
this.mMapView.postInvalidate();

自定义叠加类，不需要，但保持整洁。

public class PinsOverlay extends Overlay
{
    public PinsOverlay()
    {
        super();
    }
    @Override
    public boolean draw(final Canvas canvas, final MapView mapView, final boolean shadow, final long when)
    {
        super.draw(canvas, mapView, shadow);
        // draw your pins here
        return true;
    }
}