java比较器comparator使用示例分享

import java.util.arraylist;
import java.util.collections;
import java.util.comparator;
import java.util.list;

public class comparatortest implements comparator<stuentity> {

    /**
     * @param args
     */
    public static void main(string[] args) {
        list<stuentity> list = new arraylist<stuentity>();
        stuentity stud1=new stuentity();
        stud1.setage(10);
        stud1.setname("abc");
        stuentity stud2=new stuentity();
        stud2.setage(10);
        stud2.setname("bdc");
        stuentity stud3=new stuentity();
        stud3.setage(5);
        stud3.setname("bdd");
        stuentity stud4=new stuentity();
        stud4.setage(30);
        stud4.setname("aad");

        list.add(stud1);
        list.add(stud2);
        list.add(stud3);
        list.add(stud4);

        collections.sort(list, new comparatortest());

        for(stuentity stud:list){
            system.out.println(stud.getage()+":"+stud.getname());
        }
    }
/**
 *
 */
    @override
    public int compare(stuentity stud1, stuentity stud2) {
        //根据姓名排序
        int maxname=stud1.getname().compareto(stud2.getname());
        if(maxname!=0)
            return maxname;
        //根据年龄排序
        int maxage=stud1.getage()-stud2.getage();
        //if(maxage!=0)
            return maxage;
    }
}

输出：

30:aad
10:abc
10:bdc
5:bdd

java的比较器很有用，实现comparator接口的compare（）这个回调方法来制定排序规则，然后调用collections.sort(list, new comparatortest());就可以将list进行排序，很方便

使用时要注意compare（）方法中的return的先后顺序，优先的排序规则要写在前面

实体类：

/**
 * 学生实体类
 *
 */
public class stuentity {
    private int studentid;// 学号
    private string name;
    private int age;
    private string sex;// 性别
    private int roomnumber;// 房间号
    private string degree;//学位
    private int grade;//年级
    private string devicenumber;// 设备号
    private int groupnumber;// 所属的小组
    private int javascore;// java成绩
    private int netscore;// net成绩
    public string getdegree() {
        return degree;
    }

    public void setdegree(string degree) {
        this.degree = degree;
    }

    public int getgrade() {
        return grade;
    }

    public void setgrade(int grade) {
        this.grade = grade;
    }

 

    /**
     * 初始化有参构造函数
     *
     * @param id
     * @param name
     * @param age
     * @param sex
     * @param roomnumber
     * @param devicenumber
     * @param groupnumber
     * @param javascore
     * @param netscore
     */
    public stuentity(string name, int age, string sex, int roomnumber,
            string devicenumber, int groupnumber, int javascore, int netscore) {
        this.name = name;
        this.age = age;
        this.sex = sex;
        this.roomnumber = roomnumber;
        this.devicenumber = devicenumber;
        this.groupnumber = groupnumber;
        this.javascore = javascore;
        this.netscore = netscore;
    }

    /**
     * 无参构造函数
     */
    public stuentity() {

    }

    public int getjavascore() {
        return javascore;
    }

    public void setjavascore(int javascore) {
        this.javascore = javascore;
    }

    public int getnetscore() {
        return netscore;
    }

    public void setnetscore(int netscore) {
        this.netscore = netscore;
    }

   

    public int getstudentid() {
        return studentid;
    }

    public void setstudentid(int studentid) {
        this.studentid = studentid;
    }

    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 string getsex() {
        return sex;
    }

    public void setsex(string sex) {
        this.sex = sex;
    }

    public int getroomnumber() {
        return roomnumber;
    }

    public void setroomnumber(int roomnumber) {
        this.roomnumber = roomnumber;
    }

    public string getdevicenumber() {
        return devicenumber;
    }

    public void setdevicenumber(string devicenumber) {
        this.devicenumber = devicenumber;
    }

    public int getgroupnumber() {
        return groupnumber;
    }

    public void setgroupnumber(int groupnumber) {
        this.groupnumber = groupnumber;
    }
}