实例：
import java.util.Objects;
public class Test04 {
public static void main(String[] args) {
Student student1 = new Student(111,"wutiaolu");
Student student2 = new Student(111,"wutiaolu");
System.out.println(student1==student2);
System.out.println(student1.equals(student2));
}
}
class Student{
int no;
String school;
public Student(){
}
public Student(int no, String school) {
this.no = no;
this.school = school;
}
@Override
public String toString() {
return "Student{" +
"no=" + no +
", school='" + school + '\'' +
'}';
}
//equals需求：当一个学生的学号相等，且学校相同时，表示同一个学生
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Student student = (Student) o;
return no == student.no &&
Objects.equals(school, student.school);
}
