【java编程】Collection类之HashSet存储自定义对象元素

/*SET集合是无序的，判断无序的方法是先比较hashcode值，如果相同
再比较equals方法*/
import java.util.*;
class hashCodeDemo
{
public static void main(String[] args)
{
HashSet hs = new HashSet();
hs.add(new Person("lisi",33));
hs.add(new Person("lisi",34));
hs.add(new Person("lisi",35));
hs.add(new Person("lisi",35));
hs.add(new Person("lisi",36));
hs.add(new Person("lisi",36));
Iterator it = hs.iterator();
while(it.hasNext())
{
//因为ArrayList里面添加对象时都被强制转换成Object类型
Person p=(Person)it.next();
System.out.println(p.getName()+"::"+p.getAge());
}
}

}
class Person
{
private String name;
private int age;
Person(String name,int age)
{
this.name=name;
this.age=age;
}
public String getName()
{
return this.name;
}
public int getAge()
{
return this.age;
}
//复写equals方法
public boolean equals(Object obj)
{
Person p = (Person)obj;
System.out.println(this.name+"......equals......"+p.getName());
return this.name.equals(p.getName()) && this.age==p.getAge();
}
//复写hashCode方法
public int hashCode()
{
System.out.println(this.name+"......hashCode");
return name.hashCode()+age*39;
}

}