Some time ago I found the MJVM project. Sadly, this project has been abandoned by it author (I asked Igor via email).
I wonder if there is a (continued) open source project of a full implementation of a JVM in Java like this one.
By "full", I mean, not only to emulate mobile devices.
An interesting Java JVM implementation is this one:
https://gitlab.com/neoexpert/jvm
It is able to run simple Java Programs and some advanced ones. It should also be able to run itself. It has also a subproject which contains an JavaScript implementation of JVM which is able to run in Browser. It is very fast. You can run the JS implementation with:
mvn clean install
cd jsjvm
./run.sh
The JavaScript implementation does have a simple JDK which contains some classes for DOM Manipulation and WebGL bindings. I am planning to implementat the JDWP (Java Debugger Wire Protocol) for it. If it is done, you will be able to connect with a Debugger (for example from IntelliJ) and debug Java code which is running in Browser.