mc

Memory compiler, compiles java files into bytecode and class files in memory.

mc /tmp/Test.java

The classloader can be specified with the -c option:

mc -c 327a647b /tmp/Test.java

The output directory can be specified with the -d option:

mc -d /tmp/output /tmp/ClassA.java /tmp/ClassB.java

After compiling the .class file, you can use the redefine command to re-define the loaded classes in JVM.