Java 如何让Android中的popupWindow正常工作？

我试图得到一个简单的弹出发生，但一个错误正在返回。错误发生在所提供代码的第四行（最后一行）。有什么建议吗

活动代码

logoutoption = new PopupWindow();
logoutoption.showAtLocation(new LinearLayout(this), Gravity.CENTER, 0, 0);
logoutoption.setBackgroundDrawable(getResources().getDrawable(drawable.logoutoption_default));
logoutoption.update(100, 50);

日志

---

替换为以下代码：

LayoutInflater layoutInflater  = (LayoutInflater)getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);  
        View popupView = layoutInflater.inflate(R.layout.logoutoption, null);  
        final PopupWindow logoutoption = new PopupWindow(popupView, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);  
        logoutoption.showAsDropDown(search, 50, -30);

LayoutInflater layoutInflater  = (LayoutInflater)getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);  
        View popupView = layoutInflater.inflate(R.layout.logoutoption, null);  
        final PopupWindow logoutoption = new PopupWindow(popupView, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);  
        logoutoption.showAsDropDown(search, 50, -30);