我想问问两个用户在排序时相等是什么意思啊

Question

我想问问两个用户在排序时是相等的是什么意思啊，要用到哪方面的知识，没有思路了，怎么做呀，谢谢了

Answer 1

package Answer7731784;

import java.util.ArrayList;
import java.util.Collections;

class User implements Comparable<User> {
    private String username;
    private String password;
    private int role;

    protected User(String username, String password, int role) {
        super();
        this.username = username;
        this.password = password;
        this.role = role;
    }

    @Override
    public int compareTo(User o) {
        return username.compareTo(o.username);
    }

    @Override
    public String toString() {
        return "\nUser [username=" + username + ", password=" + password + ", role=" + role + "]\n";
    }
    

}
public class Answer{
    public static void main(String[] args) {
        ArrayList<User> list = new ArrayList<>();
        User user1 = new User("b", "123", 0);
        list.add(user1);
        User user2 = new User("b", "4567", 0);
        list.add(user2);
        
        Collections.sort(list);//排序
        System.out.println("两个user对象"+(user1.compareTo(user2)==0?"相等":"不相等"));
        System.out.println(list);//打印排序结果
    }
}