windowManager.addView()抛出WindowManager$InvalidDisplayException异常

WindowManager.LayoutParams mParams = new WindowManager.LayoutParams(
WindowManager.LayoutParams.WRAP_CONTENT,

WindowManager.LayoutParams.WRAP_CONTENT
);

方法二：

mParams.width = WindowManager.LayoutParams.WRAP_CONTENT;mParams.height = WindowManager.LayoutParams.WRAP_CONTENT;

利用方法一构造的params，调用windowManager.addView(View,params)时，

会抛出WindowManager$InvalidDisplayException异常，原因不明。求指导！

具体异常信息如下：

android.view.WindowManager$InvalidDisplayException: Unable to add window android.view.ViewRootImpl$W@3a1248f7 -- the specified window type is not valid

at android.view.ViewRootImpl.setView(ViewRootImpl.java:594)at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:282)at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:85)at com.test.duan.myuilibrarytest.view.DradListView$override.createDragImage(DradListView.java:131)at com.test.duan.myuilibrarytest.view.DradListView$override.static$access$100(DradListView.java:21)at com.test.duan.myuilibrarytest.view.DradListView$override.access$dispatch(DradListView.java)at com.test.duan.myuilibrarytest.view.DradListView.access$100(DradListView.java:0)at com.test.duan.myuilibrarytest.view.DradListView$1.run(DradListView.java:59)at android.os.Handler.handleCallback(Handler.java:739)at android.os.Handler.dispatchMessage(Handler.java:95)at android.os.Looper.loop(Looper.java:135)at android.app.ActivityThread.main(ActivityThread.java:5254)at java.lang.reflect.Method.invoke(Native Method)at java.lang.reflect.Method.invoke(Method.java:372)at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)