HashSet

package ch3;

public class Student {
    private int age;
    private String name;
    Student(int num,String name)
    {
    	this.age =num;
    	this.name =name;
    }
	@Override
	public boolean equals(Object o) {
		// TODO Auto-generated method stub
		Student s =(Student)o;
		return  age ==s.age&&name.equals(s.name);
	}
	@Override
	public int hashCode() {
		// TODO Auto-generated method stub
		return age*name.hashCode();
	}
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return "age:" +age+"name:"+name;
					}
    
}

package ch3;

import java.util.HashSet;
import java.util.Iterator;

public class HashSetText1 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		HashSet hs = new HashSet();
		hs.add(new Student(28,"zhang"));
		hs.add(new Student(21,"zhang"));
		hs.add(new Student(28,"li"));
		hs.add(new Student(28,"zhao"));
		hs.add(new Student(28,"zhang"));//HashSet不能重复，无序
	    hs.add(null);
		Iterator in = hs.iterator();
		while(in.hasNext())
		{
			System.out.println(in.next());
		}

	}

}