标签：相同 obj str getc ali 概念 mic tag width
一、浅复制和深复制概念
浅复制（浅克隆）： 被复制对象的所有变量都含有与原来对象相同的值，而所有的对其他对象的引用仍然指向原来的对象。换言之，浅复制仅仅复制所考虑的对象，而不是复制它所引用的对象。
深复制（深克隆）： 被复制对象的所有变量都含有与原来对象相同的值，除去那些引用其他对象的变量。那些引用其他对象的变量将指向被复制过的新对象， 而不再试原有的那些被引用的对象。换言之，深复制把复制的对象所应用的对象都复制了一遍。
二、Java的Clone()方法 【定义在Object类中】
clone方法将对象复制一份并返回给调用者。
一般而言，clone() 方法满足：
1、对任何对象x，都有x.clone() != x
克隆对象与原对象不是一个对象
2、对任何的对象x，都有
x.clone().getClass() == x.getClass()
克隆对象与原对象的类型一样
3、如果对象x的equals（）方法定义恰当，那么x.clone().equals(x)应该成立
二、浅复制Demo
public class CloneTest1 { public static void main(String[] args) throws CloneNotSupportedException { Student student = new Student(); student.setAge(20); student.setName("Larry"); Student student2 = (Student)student.clone(); System.out.println(student2.getAge()); System.out.println(student2.getName()); System.out.println("-----------------------"); student2.setName("Nick"); System.out.println(student.getName()); System.out.println(student2.getName()); } } class Student implements Cloneable{ private int age; private String name; 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; } @Override public Object clone() throws CloneNotSupportedException { Object object = super.clone(); return object; } }
打印结果
20
zhangsan
-----------------------
zhangsan
Lisi
student2.setName("Nick"); 执行后，student2的name赋予新的值，指向新的空间。如下图
三、深复制
以下代码还是浅复制
public class CloneTest2 { public static void main(String[] args) throws CloneNotSupportedException { Teacher teacher = new Teacher(); teacher.setAge(40); teacher.setName("Teacher zhang"); Student2 s1 = new Student2(); s1.setAge(20); s1.setName("zhangsan"); s1.setTeacher(teacher); Student2 s2 = (Student2)s1.clone(); System.out.println(s2.getAge()); System.out.println(s2.getName()); teacher.setName("Teacher Li"); System.out.println(s2.getTeacher().getAge()); System.out.println(s2.getTeacher().getName()); } } class Teacher { private int age; private String name; 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; } } class Student2 implements Cloneable{ private int age; private String name; private Teacher teacher; 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 Teacher getTeacher() { return teacher; } public void setTeacher(Teacher teacher) { this.teacher = teacher; } @Override public Object clone() throws CloneNotSupportedException { Object object = super.clone(); return object; } }
修改成深复制
Teacher也实现Clone方法
然后改写Student的Clone方法
clone Student的时候，修改Teacher。
修改后的完整代码：
public class CloneTest2 {
public static void main(String[] args) throws CloneNotSupportedException {
Teacher teacher = new Teacher();
teacher.setAge(40);
teacher.setName("Teacher zhang");
Student2 s1 = new Student2();
s1.setAge(20);
s1.setName("zhangsan");
s1.setTeacher(teacher);
Student2 s2 = (Student2)s1.clone();
System.out.println(s2.getAge());
System.out.println(s2.getName());
teacher.setName("Teacher Li");
System.out.println(s2.getTeacher().getAge());
System.out.println(s2.getTeacher().getName());
}
}
class Teacher implements Cloneable{
private int age;
private String name;
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;
}
@Override
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
}
class Student2 implements Cloneable{
private int age;
private String name;
private Teacher teacher;
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 Teacher getTeacher() {
return teacher;
}
public void setTeacher(Teacher teacher) {
this.teacher = teacher;
}
@Override
public Object clone() throws CloneNotSupportedException {
Student2 student2 = (Student2)super.clone();
student2.setTeacher((Teacher)student2.getTeacher().clone());
return student2;
}
}
五、利用序列化来做深复制
把对象写到流里的过程是序列化（Serilization）过程，而把对象从流中读取出来的过程则叫饭序列化（Deserialization）过程。应当指出的是，写在流里的是对象的一个拷贝，而原对象仍然存在于JVM里面
使用Clone方法实现深复制存在的缺点： 存在多个引用的成员变量，将做多次处理。
如上图做了一次处理，如果有多个应用，将做多次处理。
深拷贝（deep clone）与浅拷贝（shallow clone）
标签：相同 obj str getc ali 概念 mic tag width
原文地址：https://www.cnblogs.com/linlf03/p/10850391.html
