已知有如下代码: import java.util.Date; import java.util.Objects; /** * Student继承父类的属性和方法 */ public class Student{ private String name; private Date birthday; public String getName() { return name; } public void setName(String name) { this.name = name; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = (Date)birthday.clone(); } @Override public String toString() { return "学生{" + "姓名'" + name + '\'' + ", 出生日期" + birthday + '}'; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Student student = (Student) o; return Objects.equals(name, student.name) && Objects.equals(birthday, student.birthday); } @Override public int hashCode() { return Objects.hash(birthday); } } 关于上述代码说法正确的是?