How can I trace creation of objects?

Question

I am wondering how I can trace creation of objects with new. For example:
interface CreationListener {
    void objectCreated(Object o);
class CreationNotifier {
    static void registerCreationListener(Class cls, CreationListener listener) {
        // registers `listener' to be notified after creating any object of class `cls'
class Test {
    public static void main(String[] args) {
        CreationNotifier.registerCreationListener(Integer.class, new CreationListener() {
            public void objectCreated(Object o) {
                System.out.println("Created Integer " + ((Integer)o).intValue());
        new Integer(2);  // Now I would expect to see `Created Integer 2' on my console...
}In other ways I want to get informed about every object of the specified class that gets created
throughout the application.
Does anyone have an idea about it? I was trying to find something appropriate in SecurityManager
but I failed :(
Please help!

Answer 1

I think you did not understand exactly what I meant. Your solution is only good for classes written by
me and I wanted to catch all object constructions in any class, e.g. one that I have only in a binary form.
Maybe Hashtable is
not the right data structure but I got to go back to
work :-) Let me know if you come up with a better
implementation.
-- Niladri.I created a WeakHashSet class on top of WeakHashMap which uses one static object as a value and really cares only about the keys. In the registrating class I have a HashMap with keys of type Class and values of WeakHashSet. The register method is simple:
public void register(Object o) {
    if (o == null) return;
    if (!map.containsKey(o.getClass()))    // this is the first object of this class being registered
        map.put(o.getClass(), new WeakHashSet());
    ((WeakHashSet)map.get(o.getClass())).add(o);    // WeakHashSet implements Set interface
}This design ensures (because of using WeakHashMap) that I only have live objects in my structure after running GC (in fact, I call System.gc() in methods to find the live objects of a specific class).
As you can see, my only problem is to have the object registration automate for classes that I have not written (and do not have sources).
And using the profiler is not portable (as I guess) - in examples for JProbe they used DLL's and UNIX shared objects. And that requires unusual switches when starting JVM. I would like to have an all-Java language solution as the code fragments which I have described come from a library which I am writing now and I should not make the users of it depend on switches or dynamic libraries...
Anyway, thanks for your good will. :-)