After adding a jar file to a project's lib folder and after adding it to the build.gradle file as compile'path example' when you sync the gradle it add an additional line as compile files('libs/example.jar'). You just need to remove the line you previously added to the build.gradle file i.e. the compile'path example' after the gradle sync. You also need to remove the line compile fileTree(dir: 'libs', include: '*.jar')
