@Imivan, the Android context menu only displays on Android projects. I've got STS 2.7.1 on one machine and an older version on another machine. Both of them do not display the android context menu on standard java projects. I'm not sure of an easy way to do what you are asking. One possible option is to add an AndroidManifest.xml file to the project directory and create a new Android project from existing source. Another option that may work is to manually edit the eclipse classpath and project files to include the android specific settings. For both of those options you'll probably want to look at an existing eclipse android project setup.
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