Create an object instance without calling its constructor?

Question

Hi,
Sometimes it's useful to create object instances without calling their constructor. When? For example object deserialization.
By default when deserializating an object, the instance in the VM is created by calling the default constructor of the first non Serializable super-class (if you don't have such you're in trouble). I think that the db4o object database don't even call any constructor you may have written.
So such thing exists, but how is this possible? I fugured out that sun's deserialization mechanism first finds the constructor of the first non Serializable super-class and then:
cons = reflFactory.newConstructorForSerialization(cl, cons); Here I'm stuck.
Here's the source of the method for finding serializable constructor:
     * Returns subclass-accessible no-arg constructor of first non-serializable
     * superclass, or null if none found.  Access checks are disabled on the
     * returned constructor (if any).
    private static Constructor getSerializableConstructor(Class cl) {
     Class initCl = cl;
     while (Serializable.class.isAssignableFrom(initCl)) {
         if ((initCl = initCl.getSuperclass()) == null) {
          return null;
     try {
         Constructor cons = initCl.getDeclaredConstructor(new Class[0]);
         int mods = cons.getModifiers();
         if ((mods & Modifier.PRIVATE) != 0 ||
          ((mods & (Modifier.PUBLIC | Modifier.PROTECTED)) == 0 &&
           !packageEquals(cl, initCl)))
          return null;
         cons = reflFactory.newConstructorForSerialization(cl, cons);
         cons.setAccessible(true);
         return cons;
     } catch (NoSuchMethodException ex) {
         return null;
    }So any info about this ReflectionFactory, and the problem as a whole?
Thanks.

Answer 1

So the question is how to create object instance without initializing it (calling the constructor)? And if you have any info about ReflectionFactory it will be useful too.
When serializing an object you save all its fields and some extra info. When you deserialize it you have to reconstruct it, by copying the fields back, but not to reinitialize.
import java.lang.reflect.*;
import java.io.Serializable;
import java.security.AccessController;
import sun.reflect.ReflectionFactory;
public class Test0 implements Serializable {
    public Test0() {
        System.out.println("Test0");
    public static void main(String[] args) throws Exception {
        Constructor<Test0> constr = reflectionFactory.newConstructorForSerialization(Test0.class, Object.class.getConstructor(new Class[0]));
        System.out.println(constr.newInstance(new Object[0]).getClass());
    private static final ReflectionFactory reflectionFactory = (ReflectionFactory)
     AccessController.doPrivileged(
         new ReflectionFactory.GetReflectionFactoryAction());
}When you execute this piece you get:
class Test0