field 'int android.view.View.mViewFlags' on a null object reference

java.lang.NullPointerException: Attempt to read from field ‘int android.view.View.mViewFlags’ on a null object reference

问题发生原因，自己新建了个ViewGroup对象想要加到parent view中，其中这个ViewGroup又实现了一个remove view方法。

FrameLayout parentView;ViewGroup viewGroup = new ViewGroup(this){     @Override     protected void onRemoveView(Decoration decoration) {          parentView.remove(decoration);     }};parentView.addView(viewGroup);

会导致parent边移除子视图边加子视图，形成管理混乱。所以要加上：

new Handler().post(new Runnable() {     public void run() {         parent.removeView(decoration);     }});