hashsettest.java

孙鑫JAVA从入门到精通配套练习程序。所有程序都实际运行过

//演示HashCode的用法
import java.util.*;
class HashSetTest
{
	public static void main(String[] args)
	{
		HashSet hs = new HashSet();
		hs.add(new Student(1, "zhangshan"));
		hs.add(new Student(2, "lisi"));
		hs.add(new Student(3, "wangwu"));
		hs.add(new Student(1, "zhangshan"));
		
		Iterator it = hs.iterator();
		while(it.hasNext())
		{
			System.out.println(it.next());
		}
	}
}

class Student
{
	int num;
	String name;
	Student(int num, String name)
	{
		this.num = num;
		this.name = name;
	}
	
	public String toString()
	{
		return num + ": " + name;
	}
	
	public int hashCode()
	{
		return num;
	}
	
	public boolean equals(Object o)
	{
		Student s = (Student)o;
		return (num==s.num && name.equals(s.name));
	}
}