Collections.sort()学习笔记3：自定义类的接口实现

package com.ethjava;


import java.util.ArrayList;
import java.util.List;
//自定义的类实现排序
//方法1：类实现接口
import java.util.Collections;
class Empx implements Comparable<Empx> {
    private int empno;
    private String ename;

    public int getEmpno() {
        return empno;
    }

    public void setEmpno(int empno) {
        this.empno = empno;
    }

    public String getEname() {
        return ename;
    }

    public void setEname(String ename) {
        this.ename = ename;
    }

    //构造函数
    public Empx(int empno, String ename) {
        super();
        this.empno = empno;
        this.ename = ename;
    }

    @Override
    public String toString() {
        return "empno:\t" + empno + "\tename:\t" + ename;
    }

    public int compareTo(Empx emp) {
        /*按员工编号正序排序*/
        //return this.getEmpno()-emp.getEmpno();
        /*按员工编号逆序排序*/
        //return emp.getEmpno()-this.getEmpno();
        /*按员工姓名正序排序*/
        //return this.getEname().compareTo(emp.getEname());
        /*按员工姓名逆序排序*/
        return emp.getEname().compareTo(this.getEname());

    }
}
public class Collectionlanxi2 {
        public static void main(String[] args){
            Empx emp1 = new Empx(2, "Yangxiaofen");
            Empx emp2 = new Empx(3, "Zhangmeng");
            Empx emp3 = new Empx(1, "Alex");
            List<Empx> empList = new ArrayList<>();
            empList.add(emp1);
            empList.add(emp2);
            empList.add(emp3);

            System.out.println("before sort:");
            System.out.println(empList);
            System.out.println("=========================");
            Collections.sort(empList);
            System.out.println("after sort:");
            System.out.println(empList);
            //before sort:
            //[empno:  2  ename: Yangxiaofen, empno:    3  ename: Zhangmeng, empno:  1  ename: Alex]
            //after sort: [empno:  3  ename: Zhangmeng, empno:  2  ename: Yangxiaofen, empno:    1  ename: Alex]
        }
}




参考：

https://www.cnblogs.com/yw0219/p/7222108.html?utm_source=itdadao&utm_medium=referral