java program to create HashSet and accessing each element

import java.util.*;

public class HelloWorld {
public static void main(String[] args) {
ArrayList<Integer> alist=new ArrayList<Integer>();
alist.add(30);
alist.add(10);
alist.add(12);
alist.add(9);
alist.add(15);
alist.add(10);
//assigning alist to all List
List<Integer> all=new ArrayList<Integer>(alist);
System.out.println(alist);
System.out.println(all);
//assigning alist to HashSet
HashSet<Integer> set=new HashSet<Integer>(alist);
System.out.println(set);
Book b1=new Book(1,"C++");
Book b2=new Book(2,"Java");
HashSet<Book> bset=new HashSet<Book>();
bset.add(b1);
bset.add(b2);
Iterator itr=bset.iterator();
while(itr.hasNext())
{
Book b=(Book)itr.next();
System.out.println(b.id+" "+b.name);
}
for(Book b:bset)
{
System.out.println(b.id+" "+b.name);
}
}
}

class Book
{
int id;
String name;
public Book(int id,String name)
{
this.id=id;
this.name=name;
}
}