PopupWindow中点击Spinner 显示Unable to add window android.view.ViewRoot is not valid is your activity running

在MainActivity中有一个按钮事件，点击会弹出PopupWindow

send_data.setOnClickListener(new Popup_Window()); class Popup_Window implements View.OnClickListener{ public void onClick(View v){ popupwindow_view = getLayoutInflater().inflate(R.layout.pop, null,false); //R.layout.pop 是一个自定义的xml popup_window=new PopupWindow(popupwindow_view,LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT,true); popupwindow_view.setOnTouchListener(new View.OnTouchListener() { public boolean onTouch(View v, MotionEvent event) { if(popup_window!=null && popup_window.isShowing()){ popup_window.dismiss(); popup_window=null; } return false; } }); Spinner spinner = (Spinner) popupwindow_view.findViewById(R.id.language); ArrayAdapter adapter=ArrayAdapter.createFromResource(getApplicationContext(), R.array.language, android.R.layout.simple_spinner_item); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); spinner.setAdapter(adapter); ColorDrawable dw = new ColorDrawable(Color.parseColor("#99000000")); popup_window.setBackgroundDrawable(dw); popup_window.showAtLocation(v, Gravity.CENTER, 0, 0); } }

界面出现后一点击，这个Spinner 下拉菜单，应用就会崩溃，，，，
catlog: Unable to add window is your activity running?