说说深拷贝和浅拷贝的区别?
在 Java 中，深拷贝（Deep Copy）和浅拷贝（Shallow Copy）是两种拷贝对象的方式，它们在拷贝对象的方式上有很大不同。
浅拷贝会创建一个新对象，但这个新对象的属性（字段）和原对象的属性完全相同。如果属性是基本数据类型，拷贝的是基本数据类型的值；如果属性是引用类型，拷贝的是引用地址，因此新旧对象共享同一个引用对象。
浅拷贝的实现方式为：实现 Cloneable 接口并重写 clone() 方法。
class Person implements Cloneable {
String name;
int age;
Address address;
public Person(String name, int age, Address address) {
this.name = name;
this.age = age;
this.address = address;
}
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
class Address {
String city;
public Address(String city) {
this.city = city;
}
}
public class Main {
public static void main(String[] args) throws CloneNotSupportedException {
Address address = new Address("河南省洛阳市");
Person person1 = new Person("", 18, address);
Person person2 = (Person) person1.clone();
System.out.println(person1.address == person2.address); // true
}
}深拷贝也会创建一个新对象，但会递归地复制所有的引用对象，确保新对象和原对象完全独立。新对象与原对象的任何更改都不会相互影响。
深拷贝的实现方式有：手动复制所有的引用对象，或者使用序列化与反序列化。
①、手动拷贝
class Person {
String name;
int age;
Address address;
public Person(String name, int age, Address address) {
this.name = name;
this.age = age;
this.address = address;
}
public Person(Person person) {
this.name = person.name;
this.age = person.age;
this.address = new Address(person.address.city);
}
}
class Address {
String city;
public Address(String city) {
this.city = city;
}
}
public class Main {
public static void main(String[] args) {
Address address = new Address("河南省洛阳市");
Person person1 = new Person("", 18, address);
Person person2 = new Person(person1);
System.out.println(person1.address == person2.address); // false
}
}②、序列化与反序列化
import java.io.*;
class Person implements Serializable {
String name;
int age;
Address address;
public Person(String name, int age, Address address) {
this.name = name;
this.age = age;
this.address = address;
}
public Person deepClone() throws IOException, ClassNotFoundException {
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(bos);
oos.writeObject(this);
ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
ObjectInputStream ois = new ObjectInputStream(bis);
return (Person) ois.readObject();
}
}
class Address implements Serializable {
String city;
public Address(String city) {
this.city = city;
}
}
public class Main {
public static void main(String[] args) throws IOException, ClassNotFoundException {
Address address = new Address("河南省洛阳市");
Person person1 = new Person("", 18, address);
Person person2 = person1.deepClone();
System.out.println(person1.address == person2.address); // false
}
}
THE END
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