标签：treeset   java基础   黑马程序员   

自定义一个比较器，对TreeSet 集合中的元素按指定方法来排序

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

//自定义一个比较器
class Mycompare implements Comparator
{

	@Override
	public int compare(Object o1, Object o2) {
		// TODO Auto-generated method stub
		MinStudent ms1=(MinStudent )o1;
		MinStudent ms2=(MinStudent )o2;
		int i=ms1.getName().compareTo(ms2.getName());
		if(i==0)
			return ms1.getAge()-ms2.getAge();
		return i;
	}
	}
public class MyCompareDemos {

	public static void main(String[] args) {
		// TODO Auto-generated method stub

		TreeSet ts = new TreeSet(new Mycompare());
		ts.add(new MinStudent("ccc",22));
		ts.add(new MinStudent("ddd",22));
		ts.add(new MinStudent("aaa",21));
		ts.add(new MinStudent("dad",23));
		ts.add(new MinStudent("fff",25));
		ts.add(new MinStudent("sss",22));
		ts.add(new MinStudent("jjj",20));
		Iterator it = ts.iterator();
		while(it.hasNext())
		{
			MinStudent ms = (MinStudent)it.next();
			System.out.println(ms.toString());
		}
	}

}

class MinStudent implements Comparable
{

	public int getName;
	private String name ;
	private int age;
	MinStudent(String name ,int age)
	{
		this.name =  name ;
		this.age=age;
	}
	public int getAge()
	{
		return age;
	}
	public String getName()
	{
		return name;
	}
	public String toString()
	{
		return "name:"+name +" --- age"+age;
			
	}

	@Override
	public int compareTo(Object o) {
		// 
		MinStudent s =(MinStudent) o;
		//先按照年龄排序
		int i=this.getAge()-s.getAge();
		if(i ==0)
			return this.getName().compareTo(s.getName());
		return i;
	}
	
	}

未使用比较器前，集合中的元素顺序是》

使用比较器后：

黑马程序员——java——自定义一个比较器，对TreeSet 集合中的元素按指定方法来排序

标签：treeset   java基础   黑马程序员   

原文地址：http://blog.csdn.net/zl18603543572/article/details/46559015