浅拷贝和深拷贝

浅拷贝

浅拷贝会创建一个新对象，如果这个对象的属性是基本类型，那么拷贝的就是基本数据类型的值。如果这个对象的属性是引用数据类型，那么拷贝的就是对象的引用地址。

//实现Cloneable接口  重写clone()方法
class Thcher implements Cloneable{
    String name;

    public Thcher() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    protected Thcher clone() throws CloneNotSupportedException {
        return (Thcher) super.clone();
    }
}
class Student implements Cloneable {
    int age;
    //拷贝Thcher对象，拷贝引用地址。
    Thcher thcher;

    public Student() {
    }

    public int getAge() {
        return age;
    }

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

    public Thcher getThcher() {
        return thcher;
    }

    public void setThcher(Thcher thcher) {
        this.thcher = thcher;
    }

    //浅拷贝，直接调用父类方法
    @Override
    protected Student clone() throws CloneNotSupportedException {

        return (Student) super.clone();
    }
}

public class CopyTest {

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


        Student student = new Student();

        student.age = 1;
        student.thcher = new Thcher();
        student.thcher.name = "xiaowang";

        Student stu2 = student.clone();
		//拷贝会创建一个新对象
        System.out.println(stu2 == student);
		//对象中的引用数据类型的地址不变
        System.out.println(stu2.thcher == student.thcher);
    }
}

深拷贝

深拷贝会将对象的所有属性都浅拷贝一份。比如：对于引用变量来说，他会创建一个新的引用，拷贝的对象指向这个新的引用。

深拷贝相比于浅拷贝速度较慢并且花销较大

//实现Cloneable接口  重写clone()方法
class Thcher implements Cloneable{
    String name;

    public Thcher() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    protected Thcher clone() throws CloneNotSupportedException {
        return (Thcher) super.clone();
    }
}
class Student implements Cloneable {
    int age;
    Thcher thcher;

    public Student() {
    }

    public int getAge() {
        return age;
    }

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

    public Thcher getThcher() {
        return thcher;
    }

    public void setThcher(Thcher thcher) {
        this.thcher = thcher;
    }

    //深拷贝，重写clone方法
    @Override
    protected Student clone() throws CloneNotSupportedException {

        Student student = new Student();
        student.thcher = this.thcher.clone();
        student.age = this.age;
        return student;
    }
}

public class CopyTest {

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


        Student student = new Student();

        student.age = 1;
        student.thcher = new Thcher();
        student.thcher.name = "xiaowang";
		
        Student stu2 = student.clone();
		//深拷贝，创建一个新对象
        System.out.println(stu2 == student);
		//深拷贝，对象中的引用数据类型的地址不同
        System.out.println(stu2.thcher == student.thcher);
    }
}