17-集合框架-23-常用对象API(集合框架-TreeSet集合-Comparator比较器)

package cn.itcast.bean;

public class Person {
	
	private String name;
	private int age;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public int getAge() {
		return age;
	}
	public void setAge(int age) {
		this.age = age;
	}
	public Person(String name, int age) {
		super();
		this.name = name;
		this.age = age;
	}
	

}

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package cn.itcast.treeset.demo2;

import java.util.Comparator;

import cn.itcast.bean.Person;

/**
 * 
 * 创建了一个根据Person类的name进行排序的比较器。
 *
 */

public class ComparatorByName implements Comparator{
/*查找API中java.util中TreeSet类，发现构造函数TreeSet（Comparator），发现Comparator是一个接口，可以将对象排序
 * 
 * 也是强制复写compare方法
 */

	public int compare(Object o1,Object o2){
		
		Person p1 = (Person)o1;
		Person p2 = (Person)o2;
		int temp = p1.getName().compareTo(p2.getName());
		return temp==0?p1.getAge()-p2.getAge():temp;
	}
}

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package cn.itcast.treeset.demo2;

import java.util.Iterator;
import java.util.TreeSet;

import cn.itcast.bean.Person;

public class TreeSetDemo2 {

	public static void main(String[] args) {

		TreeSet ts = new TreeSet(new ComparatorByName());
		ts.add(new Person("zhangsan", 28));
		ts.add(new Person("lisi", 21));
		ts.add(new Person("zhouqi", 29));
		ts.add(new Person("zhaoliu", 25));
		ts.add(new Person("wangwu", 29));

		Iterator it = ts.iterator();
		while (it.hasNext()) {
			Person p = (Person) it.next();
			System.out.println(p.getName() + ":" + p.getAge());
		}
	}

}