HashSetTest.java

import java.util.*;
class HashSetTest 
{
  public static void main(String[] args) 
	{
		HashSet hs = new HashSet();
		
		System.out.println(hs.add(new People("zhangshan")));
		System.out.println(hs.add(new People("lishi")));
		System.out.println(hs.add(new People("zhangshan")));

		System.out.println(hs);
	}
}

class People
{
	String name;
	public People(String name)
	{
		this.name = name;
	}
	public boolean equals(Object o)
	{
		if (this == o)
		{
			return true;
		}
		else if (o instanceof People && o!=null)
		{
			op = (People)o;
			if (this.name.equals(op.name))
			{
				return true;
			}
		}
		returen false;
	}

	public String toString()
	{
		return this.name;
	}
}