java(30) - 对象浅克隆和深克隆

来源：互联网发布：软件质量品质管理编辑：程序博客网时间：2024/04/29 23:09

一.浅克隆和深克隆的概念：

1).浅克隆：又称为浅复制，被复制的对象的所有变量都含有与原来的对象相同的值，而所有的对其他对象的引用仍然指向原来的对象。换而言之，浅复制仅仅复制所考虑的对象，而不复制它所引用的对象。

2).深克隆：又称为深复制，被复制的对象的所有变量都含有与原来的对象相同的值，除去那些引用其他对象的变量。那些引用其他对象的变量将指向被复制过的新对象，而不再是原有的那些被引用的对象。换而言之，深复制就是把要复制的对象所引用的对象都复制了一遍。

二.浅克隆实现：

<pre class="java" name="code"><strong><span style="font-size:18px;">public class Main {public static void main(String[] args) throws Exception {Student student1 = new Student();        student1.setName("张三");        student1.setSex("男");        student1.setNumber(10);        Student student2 = (Student)student1.clone();System.out.println(student2.getName() +" "+ student2.getNumber() +" "+ student2.getSex());        student1.setName("李四");System.out.println(student1.getName());System.out.println(student2.getName());System.out.println(student1 == student2);System.out.println(student1.getClass() == student2.getClass());}}class Student implements Cloneable{int number;String name;String sex;public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}@Overrideprotected Object clone() throws CloneNotSupportedException {Object obj = super.clone(); return obj;}}</span></strong>

打印：

张三 10 男
李四
张三
false
true

Object的clone方法就是浅克隆，clone()方法满足（1）.对任何对象obj，都有obj.clone()!=obj，克隆的对象与原对象不是一个对象。

三.深克隆实现（这种方式较为麻烦，一般用序列化实现）：

public class Main {public static void main(String[] args) throws Exception {Teacher teacher = new Teacher();teacher.setName("李四");teacher.setNumber(20);Student stu = new Student();stu.setName("张三");stu.setNumber(10);stu.setSex("男");stu.setTeacher(teacher);Student stu2 = (Student)stu.clone();System.out.println(stu2.getTeacher().getName());teacher.setName("王五");//如果是浅克隆则打印王五，因为teacher引用没变，变得时候teacher中的name属性System.out.println(stu2.getTeacher().getName());}}class Teacher implements Cloneable{int number;String name;public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}public String getName() {return name;}public void setName(String name) {this.name = name;}@Overrideprotected Object clone() throws CloneNotSupportedException {return super.clone();}}class Student implements Cloneable{int number;String name;String sex;    Teacher  teacher;    public Teacher getTeacher() {return teacher;}public void setTeacher(Teacher teacher) {this.teacher = teacher;}public int getNumber() {return number;}public void setNumber(int number) {this.number = number;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}@Overrideprotected Object clone() throws CloneNotSupportedException {      Student student = (Student)super.clone();student.setTeacher((Teacher)student.getTeacher().clone());return student;}}

打印：

李四
李四

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