Java如何重写object类的equals方法详解

public class Student {
 private int id;
 private String name;
 private int age;

 @Override //重写equals方法
 public boolean equals(Object obj) {
 if(obj instanceof Student){
  Student s1=(Student)obj;
  return this.id==s1.id&&this.name==s1.name&&this.age==s1.age;
 }else {
  System.out.println("错误");
  return false;
 }
 }

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

 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 getAge() {
 return age;
 }

 public void setAge(int age) {
 this.age = age;
 }
}

 public static void main(String[] args) {
 Student s1 = new Student(1,"张三",18);
 Student s2 = new Student(1,"张三",18);

 Student s3 = new Student(1,"张三",18);
 Student s4 = new Student(1,"张三",20);

 System.out.println(s1.equals(s2));

 System.out.println(s3.equals(s4));



 }