private Long id;

private String name;

public Student(Long id, String name) {

this.id = id;

this.name = name;

}

public Long getId() {

return id;

}

public void setId(Long id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

@Override

public String toString() {

return "Student{" +

"id=" + id +

", name='" + name + '\'' +

'}';

}

@Override

public boolean equals(Object o) {

if (this == o) return true;

if (o == null || getClass() != o.getClass()) return false;

Student student = (Student) o;

System.out.println("name:" + this.getName() + "-->equals:" +

(Objects.equals(id, student.id) && Objects.equals(name, student.name)) + " " + student.getName());

return Objects.equals(id, student.id) &&

Objects.equals(name, student.name);

}

@Override

public int hashCode() {

System.out.println("name:" + this.getName() + "-->hashcode:" + Objects.hash(id, name));

return Objects.hash(id, name);

}

public static void main(String[] args) {

Student student = new Student(1L, "Mai");

Student student1 = new Student(1L, "Mai");

Student student2 = new Student(2L, "Liu");

HashSet<Student> set = new HashSet<>();

set.add(student);

set.add(student1);

set.add(student2);

System.out.println(set.toString());

}