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For example, if you want to change com.example.app to my.awesome.game, then:

1. In your Project pane, click on the little gear icon ( )

1. Uncheck / De-select the Compact Empty Middle Packages option

2. Your package directory will now be broken up in individual directories

3. Individually select each directory you want to rename, and:

* Right-click it
* Select `Refactor`
* Click on `Rename`
* In the Pop-up dialog, click on `Rename Package` instead of Rename Directory
* Enter the new name and hit **Refactor**
* Allow a minute to let Android Studio update all changes
* _Note: When renaming `com` in Android Studio, it might give a warning. In such case, select **Rename All**_

1. Now open your Gradle Build File (build.gradle - Usually app or mobile). Update the applicationId to your new Package Name and Sync Gradle, if it hasn't already been updated automatically:

1. Done! Anyways, Android Studio needs to make this process a little simpler.

Taken from: http://stackoverflow.com/questions/16804093/android-studio-rename-package