gen already exists but is not a source folde解决方案

两种解决方案：

Two actions, first:

1.Right click on the project and go to "Properties"
2.Select "Java Build Path" on the left
3.Open "Source" tab
4.Click "Add Folder..." and check "gen" and "src"
second: (because the previous action asked me to remove something... I do not remember what it was...)


1. Right click on the project and go to "Properties"
2. Select "Java Build Path" on the left
3. Open Libraries "tab"
4. Add an external JAR. Add the Google API that is in your android directory (android-sdk\platforms\android-yourversion
现在基本都解决了.....

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