Question

When I run the code below, why does it throw this error?

Exception in thread "main" java.lang.CloneNotSupportedException: Student
    at java.lang.Object.clone(Native Method)
    at Student.clone(Student.java:44)
    at StudentApp.main(StudentApp.java:10)

Here’s my main class:

public static void main(String[] args) throws CloneNotSupportedException {

    Address address = new Address("湖南省长沙市林科大","1234567",20);
    Student stu = new Student("诸葛亮量",20);
    stu.setAddress(address);

    Student stu2 = (Student)stu.clone();
    stu2.setAddress(new Address("湖南省常德市区","484848348",22));

    stu2.setName("张飞飞");
    stu2.setAge(23);
    stu.sayHi();
    stu2.sayHi();
}

This is Student class:

public class Student{

    private String name;
    private int age;
    private Address address;

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

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

    public Student() {
        super();
    }

    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    public void sayHi() {
        System.out.println("大家好，我是" + this.getName() + "同学，我今年" + this.getAge()
                + "岁了……我的HashCode是：" + this.hashCode()+"。我家庭住址是"+address.getAddress()+"，家庭住址的HashCode为："+address.hashCode());
    }

}

This is Address Class:

public class Address {

    private String address;
    private String tel;
    private int roadNum;

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getTel() {
        return tel;
    }

    public void setTel(String tel) {
        this.tel = tel;
    }

    public int getRoadNum() {
        return roadNum;
    }

    public void setRoadNum(int roadNum) {
        this.roadNum = roadNum;
    }

    public Address() {
        super();
    }

    public Address(String address, String tel, int roadNum) {
        super();
        this.address = address;
        this.tel = tel;
        this.roadNum = roadNum;
    }

}

Answer 1

From the javadoc

Invoking Object’s clone method on an instance that does not implement
the Cloneable interface results in the exception
CloneNotSupportedException being thrown.

Have you tried to make your Student class implement the Cloneable interface?