I want to create a drawing/ rendering context without initialising the memory first, so that unless a background(255); type command is issued the user is presented with the dirty memory state subsequent to issuing the size(x, y, renderer); method.

Is this possible through modifying the processing source code, or does Java do some clean up that cannot be overridden?

Just need to know whether its possible, really. I'm downloading the source for a rummage, but thought I might save some time by asking first.

Many thanks.

I doubt that's what mh wants-- the contents of memory would be more visually interesting than random noise (e.g. big sparse arrays would look stripy, images would be vaguely make-outable).

But anyhoo, it's true there's no way to do it in Java-- the VM sets all allocated space to zero as a security feature.

I think if you made a native method using JNI, you could malloc() memory in there, and return it so it could be copied into a PImage.  That would give you an image of discarded bytes from the JVM's heap.