概念
浅拷贝
拷贝出当前对象的一个副本，这个新对象和当前对象处于不同的堆内存中，两个对象的基本数据类型的值完全一样，但是引用数据类型还是指向同一个对象的。
深拷贝
深拷贝比浅拷贝更进一步，拷贝出当前对象的一个副本，这个新对象和当前对象处于不同的堆内存中，两个对象的基本数据类型的值完全一样，引用数据类型指向的对象也拷贝出了一份一模一样的副本。
深拷贝和浅拷贝对比
如何使用
1、需要拷贝的对象必须实现 Cloneable 接口
2、重写java.lang.Object类中的 clone() 方法
3、在 clone() 方法中调用 super.clone()
浅拷贝示例
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public class Address {
private String country;
private String province;
public Address() {
}
public Address(String country, String province) {
this.country = country;
this.province = province;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
@Override
public String toString() {
return "Address{" +
"country='" + country + '\'' +
", province='" + province + '\'' +
'}';
}
}
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public class Student implements Cloneable {
private int age;
private String name;
private Address address;
public Student() {
}
public Student(int age, String name, Address address) {
this.age = age;
this.name = name;
this.address = address;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "Student{" +
"age=" + age +
", name='" + name + '\'' +
", address=" + address +
'}';
}
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
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public class Main {
public static void main(String[] args) throws CloneNotSupportedException {
Student s1 = new Student(20, "a", new Address("中国", "张家界"));
Student s2 = (Student) s1.clone();
System.out.println(s1);
System.out.println(s2);
System.out.println(s1 == s2);
System.out.println(s1.getAddress() == s2.getAddress());
}
}
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| //运行结果
Student{age=20, name='a', address=Address{country='中国', province='张家界'}}
Student{age=20, name='a', address=Address{country='中国', province='张家界'}}
false
true
|
深拷贝示例
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public class Address implements Cloneable {
private String country;
private String province;
public Address() {
}
public Address(String country, String province) {
this.country = country;
this.province = province;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
@Override
public String toString() {
return "Address{" +
"country='" + country + '\'' +
", province='" + province + '\'' +
'}';
}
@Override
protected Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
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public class Student implements Cloneable {
private int age;
private String name;
private Address address;
public Student() {
}
public Student(int age, String name, Address address) {
this.age = age;
this.name = name;
this.address = address;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
@Override
public String toString() {
return "Student{" +
"age=" + age +
", name='" + name + '\'' +
", address=" + address +
'}';
}
@Override
protected Object clone() throws CloneNotSupportedException {
Student student = (Student) super.clone();
student.address = (Address) address.clone();
return student;
}
}
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public class Main {
public static void main(String[] args) throws CloneNotSupportedException {
Student s1 = new Student(20, "a", new Address("中国", "张家界"));
Student s2 = (Student) s1.clone();
System.out.println(s1);
System.out.println(s2);
System.out.println(s1 == s2);
System.out.println(s1.getAddress() == s2.getAddress());
}
}
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| //运行结果
Student{age=20, name='a', address=Address{country='中国', province='张家界'}}
Student{age=20, name='a', address=Address{country='中国', province='张家界'}}
false
false
|
参考