[Android] SDK location not found. Define location with sdk.dir in the local.properties file or with an ANDROID_HOME environment variable

從網路上下載了一個範例，開啟時會顯示這個錯誤：

I recently tried to import sample Android games I downloaded from Google’s developer website. After importing them into Android Studio, I’m getting the following error:

Error: SDK location not found. Define location with sdk.dir in the local.properties file or with an ANDROID_HOME environment variable.

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解法：

The project might be missing a settings.gradle file. Make sure that file exists from the project you are importing. If not add the settings.gradle file with the following :

include ':app'

Save the file and put it at the top level folder in your project.