Originally posted by Jeroen Wenting: In fact, part of the JVM and other tools are written in Java with a C++/Asm wrapper
Yep, the javac compiler and most of the other tools like javap, javah, etc are, indeed, written in Java. I'm not sure about the claim that part of Sun's JVM is itself written in Java; I suspect that it would come down to a semantic argument at the end, whether a particular bit of code was part of the JVM or part of the library. 99% of the APIs are written in Java, of course, with an occasional native method here and there.
except for the initial classloader all classloaders are for example written in Java. While part of the standard API, the JVM itself can't work without them as they're what loads your application classes.
Grey area of course where the standard API is an inseperable part of the JVM