Is it possible to have the System ClassLoader load .class files specified at run time?

Question

I am writing a static analysis tool for an assignment, it analyses Java bytecode using the ASM library. One of the parts of ASM that we use requires (or at least, appears to

Answer 1

First of all, ASM can be used in a such way that it won't use ClassLoader to obtain information about classes.

There are several places in ASM framework where it loads classes by default but all those places can be overridden in your own subclasses. Out of the top of my head:

• ClassWriter.getCommonSuperClass() method is called only when ClassWriter.COMPUTE_FRAMES flag is used and can be overwriten to not use ClassLoader to get inforamtion about classes. You can find an example of that in ClassWriterComputeFramesTest that introduces a ClassInfo abstraction
• Similarly SimpleVerifier.getClass() method is used by SimpleVerifier.isAssignableFrom() and you can overwrite the latter and use the ClassInfo abstraction to find the common super type. If I am not mistaken, AspectWerkz project had implemented similar thing in its type pattern matching code. Also note that there is SimpleVerifier.setClassLoader() method, which you can use if you still want to load your own classes.

On a side note, on a Sun's JVMs, loaded classes gets to PermGen area and can't be unloaded, so it is not a good idea to load classes only for static code analysis purposes if you can avoid that, especially if tool would be integrated into a long-live process, such as IDE.