集合训练5

下面的代码输出什么?

已知:Person类按照id和name重写了hashCode和equals方法,问下面代码输出什么?

import java.util.HashSet;
import java.util.Objects;

public class Homework05 {
    public static void main(String[] args) {
        HashSet set = new HashSet();
        Person p1 = new Person(1001,"AA");
        Person p2 = new Person(1002,"BB");
        set.add(p1);
        set.add(p2);
        p1.name = "CC";
        set.remove(p1);
        System.out.println(set);
        set.add(new Person(1001,"CC"));
        System.out.println(set);
        set.add(new Person(1001,"AA"));
        System.out.println(set);

    }
}

class Person{
    private int id;
    public String name;

    public Person(int id, String name) {
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Person person = (Person) o;
        return id == person.id &&
                Objects.equals(name, person.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, name);
    }

    @Override
    public String toString() {
        return "person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

试写出Vector和ArrayList的比较?

posted @ 2022-01-20 13:32  摘星丶仙  阅读(17)  评论(0)    收藏  举报