我有以下代码在活动顶部添加View并在10秒后删除它。
public class MyActivity extends MainActivity {
@Override
protected void onCreate(Bundle arg0) {
super.onCreate(arg0);
final ImageView view = new ImageView(this);
view.setBackgroundColor(Color.WHITE);
getWindowManager()
.addView(
view,
new WindowManager.LayoutParams(LayoutParams.MATCH_PARENT,
LayoutParams.MATCH_PARENT));
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
view.setVisibility(View.GONE);
getWindowManager().removeView(view);
}
}, 10000);
}
}
但这里发生了两件事: 首先,ImageView并不是最重要的,我甚至没有在显示器上看到它。 其次,10秒后发生以下错误并且应用程序崩溃
Window Session Crash
java.lang.NullPointerException
at com.android.server.wm.WindowManagerService.relayoutWindow(WindowManagerService.java:2784)
at com.android.server.wm.Session.relayout(Session.java:157)
at android.view.IWindowSession$Stub.onTransact(IWindowSession.java:154)
at com.android.server.wm.Session.onTransact(Session.java:111)
at android.os.Binder.execTransact(Binder.java:320)
at dalvik.system.NativeStart.run(Native Method)
FATAL EXCEPTION: main
java.lang.NullPointerException
at android.os.Parcel.readException(Parcel.java:1327)
at android.os.Parcel.readException(Parcel.java:1275)
at android.view.IWindowSession$Stub$Proxy.relayout(IWindowSession.java:616)
at android.view.ViewRoot.relayoutWindow(ViewRoot.java:3104)
at android.view.ViewRoot.performTraversals(ViewRoot.java:1030)
at android.view.ViewRoot.handleMessage(ViewRoot.java:2020)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:132)
at android.app.ActivityThread.main(ActivityThread.java:4028)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分:0)
所以你可以这样做:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final LinearLayout linearLayout = (LinearLayout) findViewById(R.id.id_mainlinearlayout);
// final ImageView view = (ImageView) findViewById(R.id.id_imageview);
final ImageView view = new ImageView(this);
view.setBackgroundColor(Color.WHITE);
linearLayout.addView(view, new WindowManager.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
view.setVisibility(View.GONE);
linearLayout.removeView(view);
}
}, 10000);
}
并在“main.xml”中的linearLayout上添加id(对我来说:“id_mainlinearlayout”)
对我来说很好。还有另一种解决方案,您可以在xml中定义imageView,然后返回注释行。
如果要在活动顶部添加imageView,则需要使用relativeLayout并将imageView与attribut“layout_alignParentTop”放在一起。
希望会有所帮助。Ps:对不起我的英语,我是法国人!