list contains比较对象需要注意的地方

List contains()比较对象，需要重写对象的equals()和hashCode()方法。

package com.kanzhun.phoenix.admin.mytest;

import java.util.ArrayList;
import java.util.List;
import java.util.Objects;

/**
 * ContainsTest
 *
 * @author jibingbing
 * @date 2018/10/30
 **/
public class ContainsTest {

    public static void main(String[] args) {
        Student student1 = new Student(1, "ji", 100);
        Student student2 = new Student(2, "ji", 100);
        Student student3 = new Student(1, "ji1", 100);

        List students = new ArrayList<>();
        students.add(student1);
//        students.add(student2);
        students.add(student3);

        System.out.println(students.contains(student2));
    }

    static class Student {
        int id;
        String name;
        int score;

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

        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;
        }

        public int getScore() {
            return score;
        }

        public void setScore(int score) {
            this.score = score;
        }

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

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