Java提高篇——对象克隆（复制）(Java进阶教程：深入理解对象克隆与复制技术)

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ithorizon 7个月前 (10-20) 阅读数 25 #后端开发

Java尽也许缩减损耗篇——对象克隆（复制）

一、概述

在Java编程中，对象的复制是一个常见的操作。有时候，我们需要创建一个与现有对象完全相同的副本，以便在不修改原始对象的情况下进行操作。Java提供了一种特殊的复制机制——对象克隆（Object Cloning）。本文将深入探讨对象克隆的原理、实现方法以及相关注意事项。

二、对象克隆的实现做法

Java中实现对象克隆首要有两种做法：浅拷贝和深拷贝。

2.1 浅拷贝

浅拷贝仅仅复制对象本身及其包含的值类型成员变量，对于引用类型成员变量，浅拷贝会复制引用，但不会复制引用的对象。下面是一个易懂的浅拷贝示例：


public class Student implements Cloneable {
    private String name;
    private int age;
    public Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}
public class Main {
    public static void main(String[] args) {
        Student original = new Student("Alice", 20);
        Student copy = (Student) original.clone();
        System.out.println(original == copy); // false
        System.out.println(original.name == copy.name); // true
        System.out.println(original.age == copy.age); // true
    }
}

2.2 深拷贝

深拷贝会复制对象本身以及对象引用的所有对象，从而实现完全自主的复制。下面是一个深拷贝的示例：


public class Student implements Cloneable {
    private String name;
    private int age;
    private Address address;
    Student(String name, int age, Address address) {
        this.name = name;
        this.age = age;
        this.address = address;
    }
    @Override
    protected Object clone() throws CloneNotSupportedException {
        Student copy = (Student) super.clone();
        copy.address = (Address) this.address.clone();
        return copy;
    }
}
class Address implements Cloneable {
    private String street;
    private String city;
    Address(String street, String city) {
        this.street = street;
        this.city = city;
    }
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}
public class Main {
    public static void main(String[] args) {
        Address address = new Address("123 Street", "New York");
        Student original = new Student("Alice", 20, address);
        Student copy = (Student) original.clone();
        System.out.println(original == copy); // false
        System.out.println(original.name == copy.name); // true
        System.out.println(original.age == copy.age); // true
        System.out.println(original.address == copy.address); // false
    }
}