我试图通过演示序列GroundOverlay
来显示Google地图上的渐进式雷达图像,这些图像使用预设的雷达图像阵列。为了不使用户界面繁忙,我正在为此使用不同的线程。不幸的是,这似乎是一个奇怪的NullPointerException
正在发生。我调试了代码,并没有找到任何可能导致此错误的空变量。Handler上的NullPointerException Runnable函数
我该怎么办? (请注意,雷达覆盖,地图,图像,图像索引和MAP_BOUNDS是全局变量,不为空 - 请参阅1)。
编辑 - 简化下面的代码。仍然给出完全相同的错误。
public void createLooper() {
final Runnable runnable = new Runnable() {
public void run() {
if(run == true) {
mHandler.postDelayed(this,500);
} else {
return;
}
if(radaroverlay != null) {
radaroverlay.remove();
}
// Problem happens in the line below.
try {
GroundOverlayOptions opts = new GroundOverlayOptions()
.image(images[image_index])
.positionFromBounds(MAP_BOUNDS)
.transparency((float) 0.3);
radaroverlay = map.addGroundOverlay(opts);
} catch (Exception e) {
e.printStackTrace();
run = false;
}
if(image_index == 19) {
image_index = 0;
} else {
image_index++;
}
}
};
//mHandler.postDelayed(runnable, 500);
new Thread(runnable).start();
和相应logcat
02-27 16:58:04.815: E/AndroidRuntime(6791): FATAL EXCEPTION: main
02-27 16:58:04.815: E/AndroidRuntime(6791): java.lang.NullPointerException
02-27 16:58:04.815: E/AndroidRuntime(6791): at maps.z.aa.<init>(Unknown Source)
02-27 16:58:04.815: E/AndroidRuntime(6791): at maps.z.bi.a(Unknown Source)
02-27 16:58:04.815: E/AndroidRuntime(6791): at maps.z.bi.b(Unknown Source)
02-27 16:58:04.815: E/AndroidRuntime(6791): at maps.z.ag.addGroundOverlay(Unknown Source)
02-27 16:58:04.815: E/AndroidRuntime(6791): at com.google.android.gms.maps.internal.IGoogleMapDelegate$Stub.onTransact(IGoogleMapDelegate.java:182)
02-27 16:58:04.815: E/AndroidRuntime(6791): at android.os.Binder.transact(Binder.java:249)
02-27 16:58:04.815: E/AndroidRuntime(6791): at com.google.android.gms.maps.internal.IGoogleMapDelegate$a$a.addGroundOverlay(Unknown Source)
02-27 16:58:04.815: E/AndroidRuntime(6791): at com.google.android.gms.maps.GoogleMap.addGroundOverlay(Unknown Source)
02-27 16:58:04.815: E/AndroidRuntime(6791): at com.aquamet.saramap.MapActivity$2$1.run(MapActivity.java:520)
02-27 16:58:04.815: E/AndroidRuntime(6791): at android.os.Handler.handleCallback(Handler.java:587)
02-27 16:58:04.815: E/AndroidRuntime(6791): at android.os.Handler.dispatchMessage(Handler.java:92)
02-27 16:58:04.815: E/AndroidRuntime(6791): at android.os.Looper.loop(Looper.java:123)
02-27 16:58:04.815: E/AndroidRuntime(6791): at android.app.ActivityThread.main(ActivityThread.java:4627)
02-27 16:58:04.815: E/AndroidRuntime(6791): at java.lang.reflect.Method.invokeNative(Native Method)
02-27 16:58:04.815: E/AndroidRuntime(6791): at java.lang.reflect.Method.invoke(Method.java:521)
02-27 16:58:04.815: E/AndroidRuntime(6791): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:876)
02-27 16:58:04.815: E/AndroidRuntime(6791): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:634)
02-27 16:58:04.815: E/AndroidRuntime(6791): at dalvik.system.NativeStart.main(Native Method)
调试:
很难说只用这个代码,但我想,当你设定的地图地面叠加层,你的图像索引可以不填充或上升到19是不是20个项目? – 2013-02-27 20:58:06
另外,如果radaroverlay不为null,您是否想要删除它?或者你想只是将它设置为空? – 2013-02-27 21:00:10
这是一个动画,所以我需要删除一个覆盖,然后添加一个新的。那有意义吗? – jhc 2013-02-27 21:03:05