Java-深拷贝(deep copy)

野性酷女 2021-09-28 22:38 594阅读 0赞

1. 首先Java的[clone()][clone]方法，我们已经了解

2. 接着clone()方法的[浅拷贝][Link 1]，浅拷贝有一些不尽人意的地方

3. 目的：

为了解决不如意，

为了解决修改clone()得到的新对象不会影响被复制对象的字段的问题，

我们需要实现深拷贝(deep copy)。

4. 示例：

package com.basis.entity;
    
    public class Person implements Cloneable {
    
        private String adress;
        private Info info;
    
        public String getAdress() {
            return adress;
        }
    
        public void setAdress(String adress) {
            this.adress = adress;
        }
    
        public Info getInfo() {
            return info;
        }
    
        public void setInfo(Info info) {
            this.info = info;
        }
    
        @Override
        public String toString() {
            return "Person{" +
                    "adress='" + adress + '\'' +
                    ", info=" + info +
                    '}';
        }
    
        public Object clone() throws CloneNotSupportedException{
            Person person = (Person) super.clone();
            person.info = (Info) info.clone();
            return person;
        }
    }

package com.basis.entity;
    
    public class Info implements Cloneable {
    
        private String IDCard;
        private String name;
    
        public String getIDCard() {
            return IDCard;
        }
    
        public void setIDCard(String IDCard) {
            this.IDCard = IDCard;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        @Override
        public String toString() {
            return "Info{" +
                    "IDCard='" + IDCard + '\'' +
                    ", name='" + name + '\'' +
                    '}';
        }
    
        public Object clone() throws CloneNotSupportedException{
            return super.clone();
        }
    }

package com.company;
    
    import com.basis.entity.Info;
    import com.basis.entity.Person;
    
    public class Main {
    
        public static void main(String[] args) {
    
            Info info = new Info();
            info.setName("张三");
            info.setIDCard("111111");
    
            Person person1 = new Person();
            person1.setAdress("北京");
            person1.setInfo(info);
    
            System.out.println("clone()前person1："+person1.toString());
    
            Person person2 = null;
            try {
                person2 = (Person)person1.clone();
                person2.setAdress("河南");
                Info info1 = person2.getInfo();
                info1.setName("李四");
                info1.setIDCard("222222");
                person2.setInfo(info1);
            } catch (CloneNotSupportedException e) {
                e.printStackTrace();
            }
            System.out.println("clone()后person1："+person1.toString());
            System.out.println("clone()后person2："+person2.toString());
    
        }
    }

5. 结果：

clone()前person1：Person{adress='北京', info=Info{IDCard='111111', name='张三'}}
    clone()后person1：Person{adress='北京', info=Info{IDCard='111111', name='张三'}}
    clone()后person2：Person{adress='河南', info=Info{IDCard='222222', name='李四'}}

6. 完美解决

[clone]: https://blog.csdn.net/qq_31150365/article/details/90898159
[Link 1]: https://blog.csdn.net/qq_31150365/article/details/90902246