How ObjectInputStream.readObject() works??

Question

Below is Test.java, some codes on simple serialization operations (copied from a book.) A "Blip1" object is created, serialized to a file, then deserialized back from the file. Everything works fine!!
My question is, why does the last line work, "b1 = (Blip1)in.readObject();" ?
I mean, ObjectInputStream is part of [package java.io], how can we create a "Blip1" object of [package anypackage] while we are inside [package java.io]?? Am I missing something fundamental?
I thought this ObjectInputStream.readObject() is based on Reflection, that is, ObjectInputStream.readObject() created the "Blip1" object based on the class name. So I wrote Creator.java (see below) and the result was an IllegalAccessException --- we cannot create a "Blip1" object while we are inside another package. This shows that ObjectInputStream.readObject() is not really based on Reflection(??)
How does ObjectInputStream.readObject() work??
//Test.java
package anypackage;
class Blip1 implements Externalizable {
  public Blip1() {System.out.println("Blip1 created");}
  public void writeExternal(ObjectOutput out) throws IOException {}
  public void readExternal(ObjectInput in)
    throws IOException, ClassNotFoundException {}
public class Test {
  public static void main(String[] args)
  throws IOException, ClassNotFoundException {
    System.out.println("Constructing objects:");
    Blip1 b1 = new Blip1();
    ObjectOutputStream o = new ObjectOutputStream(
      new FileOutputStream("Blips.out"));
    System.out.println("Saving objects:");
    o.writeObject(b1);
    o.close();
    // Now get them back:
    ObjectInputStream in =
      new ObjectInputStream(
        new FileInputStream("Blips.out"));
    System.out.println("Recovering b1:");
    b1 = (Blip1)in.readObject();
//Creator.java
package anyotherpackage;
import java.util.*;
public class Creator{
  Object o;
  public Creator(){
    try{
      Class c = Class.forName("anypackage.Blip1");
      Object o = c.newInstance();
    } catch (Exception e){
      System.out.println(e);
  public static void main(String[] args){
    Creator c = new Creator();
}

Answer 1

As far as i understand the ObjectInputStream.readObject() create object by recursively building the memory owned by the object, obviously object Ctor is not called (otherwise serializeable classes were forced to have empty Ctor).
It goes like this -
1)when object implements Serializable interface its stream hold description of the the object memory (for each datamember we will have something like offset,datamember type, and streamed datamember), ObjectInputStream.readObject build the datamembers recursively (recursion is stopped when we have primitive type datamember)
2)when object implements Externalizable interface the programmer is responsible to stream object's datamembers to the ObjectOutput and to read them from the ObjectInput, ObjectInputStream is responsible to create an empty object for you
anyway no Ctors are involved