Java深克隆基础讲解，通俗易懂

克隆分来浅克隆、深度克隆。要想实现克隆必须要

浅克隆：A = B.clone(), A == B 为true，即指向内存地址相同
深克隆：A = B.clone(), A == B 为false，即内存地址不同，是两个独立的对象

如何实现深克隆，例如：A类中有成员变量为B类，A类与B类要同时实现cloneable接口和重写clone方法并在A的clone()中调用B类的克隆方法给成员变量赋值才能实现深克隆

//深克隆示例：

public class Student implements Cloneable{
    private int age;
    private String name;
    private Integer code;
    @Override
    protected Teacher clone() throws CloneNotSupportedException {
        Teacher tea = (Teacher)super.clone();
        tea.student = (Student) tea.student.clone();
        return tea;
    }
    public static void main(String[] args) throws CloneNotSupportedException {
        Teacher teacher = new Teacher();
        Student student = new Student();
        student.setAge(18);
        student.setCode(18);
        student.setName("AStundent");
        teacher.setAge(10);
        teacher.setCode(1);
        teacher.setName("ATeacher");
        teacher.setStudent(student);
        Teacher clone = teacher.clone();
        
        //false,表示空间地址不同了
        System.out.println(clone.student == teacher.student);
        //false,表示空间地址不同了
        System.out.println(clone == teacher);
        
        /**
        深度克隆后发现，两对象String所指向的地址相同，不仅仅是String，
        其他几个成员变量地址也相同，为什么深度拷贝后这些成员变量的地址还相同？
        这是因为有常量池的存在例如：String a = "1"与String b = "1"的地址就是相同的
        a == b，都指向了java内存中的常量池中，当你修改a = "2"时，a会指向"2"所在常量池中的地址
        而不是将a所指向内存地址中的值改为"2"，因此修改后 a != b
        
        **/
        //true
        System.out.println(clone.getName() == teacher.getName());
        
        /**
        更改过后变为false，地址不同了
        **/
        clone.setName("change");
        //false
        System.out.println(clone.getName() == teacher.getName());
    }
}

public class Teacher implements Cloneable{
    private int age;
    private String name;
    private Integer code;
    private Student student;

    @Override
    protected Object clone() throws CloneNotSupportedException {

        return super.clone();
    }
}