android studio 新建一個專案，卻出現Design editor is unavailable until after a successful project sync

waiting for build to finish

點選工具欄File -> sync project with Gradle Files

結果build 失敗，系統提示：Failed to find Build Tools revision 28.0.2

在專案根目錄下local.properties檔案中看到：

sdk.dir=C\:\\Users\\Gouge Penguins\\AppData\\Local\\Android\\Sdk

於是到C:\Users\Gouge Penguins\AppData\Local\Android\Sdk下尋找sdk，該目錄下ls看到：

build-tools/  emulator/  extras/  patcher/  platforms/  platform-tools/  sources/  system-images/  tools/

於是cd build-tools看到

28.0.3/

Android studio需要的build tool和sdk中的版本不一致，於是在Failed to find Build Tools revision 28.0.2 有install Build Tools revision 28.0.2，點選即可下載