In Android, Dalvik was the process virtual machine (VM) that helped to execute native applications on the platform, but it was replaced in Android L (API 21) by Android Runtime (ART), another runtime environment that introduces use of the ahead-of-time (AOT) compilation. For more information, see here:
One issue found in Dalvik (that will remain unfixed) is, incorrectly allowing subclasses to override package-private methods. Developers are now issued a warning in Android Runtime.
An example could include:
Due to Google fixing a bug in Android where in previous versions, you are no longer able to incorrectly override methods that were declared as package private (meaning they have no specific access-level modifiers).
From 5.0 forward, you will need to explicitly declare protected or public as access modifiers for the methods you are to override. For more information as to how to resolve this issue, please look at the following Android documentation.
Keywords: Dalvik, ART, Object Model, Security