package devamnuals.com;

import java.util.AbstractSet;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;

class AbsSet extends AbstractSet {
  Set set;
  public AbsSet() {
	  set= new TreeSet();
  }
  public boolean add(Object e) {
	    set.add(e);
	    System.out.println(e);
	    return true;
  }
  public Iterator iterator() {
    Iterator it = set.iterator();
    while(it.hasNext())
    System.out.println(it.next());
	  return null;
  }
  public int size() {
    System.out.println(set.size());
	  return 0;
  }
 public boolean isEmpty() {
    System.out.println("Is set empty : "+set.isEmpty());
	  return true;
  }
}
public class AbstractSetDemo {
  public static void main(String args[]) {
   AbsSet aset=new AbsSet();
   System.out.println("Elements of Set=");
 for(int i=0; i<=4;i++){
	 aset.add(i);
 }
 System.out.println("Display the elements of set using iterator = ");
 aset.iterator();
 System.out.println("Size of set = ");
 aset.size();
 aset.isEmpty();
  }
}