android studio問題rendering problems no render target selected

activity_main.xml選擇Design顯示rendering problems no render target selected

在stackOverflow上找到了答案：

You need to run the AVD Manager to add a virtual device that matches the target API version your project is set to.

Click Tools->Android->AVD Manager. Click on 'New', add virtual devices targeting higher API levels, e.g 18, 19, etc.

Then restart Android Studio, and open your project, it should find a target device to allow you access to the Design view.

 

就是新建一個虛擬機，api選擇高點，我選的21，重啟成功。。。