There is no single Java VM. There's a specification with a significant number of different implementations, and the OpenJDK-based one is far from the only one i

There is no single Java VM. There's a specification with a significant number of different implementations, and the OpenJDK-based one is far from the only one in use today. Also code is still compiled to the same format that the Dalvik VM consumed. ART is just a different system for getting from Java bytecode to something executable.