defaultConfig {
applicationId "WHATEVER_THIS_IS"
}
needs to match android>app>src>main>java>com>app_name>MainActivity.java line one:
package WHATEVER_THIS_IS;
needs to match android>app>src>main>java>com>app_name>MainApplication.java line one:
package WHATEVER_THIS_IS;
needs to match android>app>src>AndroidManifest.xml
package="WHATEVER_THIS_IS">
-----
android/app/src/main/java/com/PROJECT_NAME/MainActivity.java:
package MY.APP.ID;
In android/app/src/main/java/com/PROJECT_NAME/MainApplication.java:
package MY.APP.ID;
In android/app/src/main/AndroidManifest.xml:
package="MY.APP.ID"
And in android/app/build.gradle:
applicationId "MY.APP.ID"
http://stackoverflow.com/questions/37389905/change-package-name-for-android-in-react-native
http://stackoverflow.com/questions/35131769/error-type-3-activity-class-com-awesome-project-com-awesome-project-mainactiv