How to understand the Vector source code for function elements()?

Question

hello all:
This following code snippet is extracted from java.util.Vector source code.
who can tell me how i can understand what the function nextElement does?
thank you
public Enumeration elements() {
     return new Enumeration() {
         int count = 0;
         public boolean hasMoreElements() {
          return count < this.num_elem;
         public Object nextElement() {
          synchronized (Vector.this) {   //???
              if (count < elementCount) {//???
               return elementData[count++];
          throw new NoSuchElementException("Vector Enumeration");
    }

Answer 1

Perhaps code would help more. This codeimport java.util.Vector;
import java.util.Enumeration;
import java.util.Iterator;
public class Test {
    public static void main(String[] arghs) {
     Vector v = new Vector();
     Integer two = new Integer(2);
     // Fill the Vector
     v.add("One");
     v.add(two);
     v.add(new StringBuffer("Three"));
     // Enumerate through the objects in the vector
     System.out.println("---- Enumeration ----");
     Enumeration e = v.elements();
     while (e.hasMoreElements()) System.out.println(e.nextElement());
     // Loop through the objects in the vector
     System.out.println("---- Loop ----");
     for (int i=0; i<v.size(); i++) System.out.println(v.get(i));
     // Iterate through the objects in the vector
     System.out.println("---- Iterator ----");
     Iterator i = v.iterator();
     while (i.hasNext()) System.out.println(i.next());
}produces this output
---- Enumeration ----
One
2
Three
---- Loop ----
One
2
Three
---- Iterator ----
One
2
Three
So, for a Vector, all three do the same thing. However, Iterator is part of the Collection Framework (see [url http://java.sun.com/j2se/1.4.2/docs/guide/collections/index.html]here). This allows you to treat a whole bunch of [url http://java.sun.com/j2se/1.4.2/docs/guide/collections/reference.html]objects which implement the Collection interface all the same way. I know this is way more than you were asking, but I hope it at least clears up what you were asking.