【Java工兵】浅拷贝和深拷贝

来源：互联网发布：用编程解决实际问题编辑：程序博客网时间：2024/04/27 19:09

本文将简单介绍java中对象的浅拷贝和深拷贝知识点！

Java中通过对象的clone方法可以复制对象，而clone方法在Object里定义的，是一个protected类型的方法，只有实现了Cloneable（java.lang.Cloneable）接口，该类对象才能调用clone方法，否则抛出异常。

1.浅拷贝

对象经过浅拷贝，基本类型的属性会拷贝值，引用类型的属性会拷贝引用。因此修改引用类型的属性值会影响另一对象！

示例代码

package com.test;public class ShallowCopyTest {static class Country{String name;Country(String name){this.name = name;}}static class Person implements Cloneable{String name;int age;Country country;Person(String name, int age, Country country){this.name = name;this.age = age;this.country = country;}@Overridepublic Object clone() throws CloneNotSupportedException {return super.clone();}}/** * @param args */public static void main(String[] args) {Person zhangsan = new Person("zhangsan", 24, new Country("China"));System.out.println("zhangsan - " + zhangsan.name + ":" + zhangsan.age + ":" + zhangsan.country.name);try {Person tom = (Person) zhangsan.clone();System.out.println("tom - " + tom.name + ":" + tom.age + ":" + tom.country.name);tom.name = "tom";tom.age = 21;tom.country.name = "USA";System.out.println("----------after----------");System.out.println("zhangsan - " + zhangsan.name + ":" + zhangsan.age + ":" + zhangsan.country.name);System.out.println("tom - " + tom.name + ":" + tom.age + ":" + tom.country.name);} catch (CloneNotSupportedException e) {e.printStackTrace();}}}

打印结果

zhangsan - zhangsan:24:Chinatom - zhangsan:24:China----------after----------zhangsan - zhangsan:24:USAtom - tom:21:USA

2.深拷贝

对象经过深拷贝，基本类型的属性会拷贝值，引用类型所指向的对象内容也会拷贝一份。因此修改引用类型的属性值不会影响另一对象！

示例代码

package com.test;public class DeepCopyTest {static class Country implements Cloneable{String name;Country(String name){this.name = name;}@Overridepublic Object clone() throws CloneNotSupportedException {return super.clone();}}static class Person implements Cloneable{String name;int age;Country country;Person(String name, int age, Country country){this.name = name;this.age = age;this.country = country;}@Overridepublic Object clone() throws CloneNotSupportedException {Person obj = (Person) super.clone();obj.country = (Country) this.country.clone();return obj;}}/** * @param args */public static void main(String[] args) {Person zhangsan = new Person("zhangsan", 24, new Country("China"));System.out.println("zhangsan - " + zhangsan.name + ":" + zhangsan.age + ":" + zhangsan.country.name);try {Person tom = (Person) zhangsan.clone();System.out.println("tom - " + tom.name + ":" + tom.age + ":" + tom.country.name);tom.name = "tom";tom.age = 21;tom.country.name = "USA";System.out.println("----------after----------");System.out.println("zhangsan - " + zhangsan.name + ":" + zhangsan.age + ":" + zhangsan.country.name);System.out.println("tom - " + tom.name + ":" + tom.age + ":" + tom.country.name);} catch (CloneNotSupportedException e) {e.printStackTrace();}}}

打印结果

zhangsan - zhangsan:24:Chinatom - zhangsan:24:China----------after----------zhangsan - zhangsan:24:Chinatom - tom:21:USA

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