JAVA深复制(深克隆)与浅复制(浅克隆)

「爱情、让人受尽委屈。」 2022-04-22 15:18 202阅读 0赞

# 浅复制与深复制概念 #

## 1.浅复制（浅克隆） ##

被复制对象的所有变量都含有与原来的对象相同的值，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，而不复制它所引用的对象。

## 2.深复制（深克隆） ##

被复制对象的所有变量都含有与原来的对象相同的值，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，而不再是原有的那些被引用的对象。换言之，深复制把要复制的对象所引用的对象都复制了一遍。

## Java的clone()方法 ##

1.clone方法将对象复制了一份并返回给调用者。一般而言，clone（）方法满足

2.对任何的对象x，都有x.clone() !=x 因为克隆对象与原对象不是同一个对象

3.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

4.如果对象x的equals()方法定义恰当，那么x.clone().equals(x)应该成立

## Java中对象的克隆 ##

1.为了获取对象的一份拷贝，我们可以利用Object类的clone()方法

2.在派生类中覆盖基类的clone()方法，并声明为public

3.在派生类的clone()方法中，调用super.clone()

4.在派生类中实现Cloneable接口

package cn.itcast.demo6;
    
    public class User implements Cloneable {
    
        private String name;
        private Integer age;
    
        
        public User(String name, Integer age) {
            super();
            this.name = name;
            this.age = age;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        @Override
        public Object clone() {
            Object o = null;
            try {
                //Object中的clone()识别出你要复制的是哪一个对象
                o = (User) super.clone();       
            } catch (CloneNotSupportedException e) {
                System.out.println(e.toString());
            }
            return o;
        }
        
        
    }

package cn.itcast.demo6;
    
    public class Test {
    	public static void main(String[] args) {
    		User u = new User("xiaoming",20);
            User u2 = (User)u.clone();
            u2.setName("lisi");
            u2.setAge(30);
            System.out.println("name="+u.getName()+","+"age="+u.getAge());
            System.out.println("name="+u2.getName()+","+"age="+u2.getAge());
    	}
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70]

## 说明： ##

为什么我们在派生类中覆盖Object的clone()方法时，一定要调用super.clone()呢？在运行时刻，Object中的clone()识别出你要复制的是哪一个对象，然后为此对象分配空间，并进行对象的复制，将原始对象的内容一一复制到新对象的存储空间中。

## 浅克隆 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70 1]

package cn.itcast.demo7;
    
    public class Professor {
    
        private String name;
        private Integer age;
        
        public Professor(String name, Integer age) {
            super();
            this.name = name;
            this.age = age;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public Integer getAge() {
            return age;
        }
        public void setAge(Integer age) {
            this.age = age;
        }
    }

package cn.itcast.demo7;
    
    public class Student implements Cloneable {
        private String name;
        private Integer age;   
        //引用
        private Professor professor;
        public Student(String name, Integer age, Professor professor) {
            super();
            this.name = name;
            this.age = age;
            this.professor = professor;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Professor getProfessor() {
            return professor;
        }
    
        public void setProfessor(Professor professor) {
            this.professor = professor;
        }
        
        @Override
        public Object clone() {
            Object o = null;
            try {
                //Object中的clone()识别出你要复制的是哪一个对象
                o = (Student) super.clone();       
            } catch (CloneNotSupportedException e) {
                System.out.println(e.toString());
            }
            return o;
        }
    }

package cn.itcast.demo7;
    
    public class Test {
    
    	public static void main(String[] args) {
    		Professor p = new Professor("wangwu", 50);
            Student s1 = new Student("xiaoming",20,p);
            Student s2 = (Student) s1.clone();
            System.out.println("name="+s1.getProfessor().getName()+","+"age="+s1.getProfessor().getAge());
            s2.getProfessor().setName("wangxiaowu");
            s2.getProfessor().setAge(10);
            System.out.println(s1);
            System.out.println(s2);
            System.out.println(p);
            System.out.println("name="+s1.getProfessor().getName()+","+"age="+s1.getProfessor().getAge());
            System.out.println("name="+s2.getProfessor().getName()+","+"age="+s2.getProfessor().getAge());
    	}
    
    }

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70 2]

## 深克隆 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MDgwNzI0Nw_size_16_color_FFFFFF_t_70 3]

package cn.itcast.demo8;
    
    public class Professor implements Cloneable {
    
        private String name;
        private Integer age;
    
        public Professor(String name, Integer age) {
            this.name = name;
            this.age = age;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Object clone() {
    
            Object o = null;
            try {
                o = super.clone();
            } catch (CloneNotSupportedException e) {
                System.out.println(e.toString());
            }
            return o;
        }
    
    }

package cn.itcast.demo8;
    
    public class Student implements Cloneable {
    
        private String name;
        private Integer age;
        private Professor professor;
    
        public Student(String name, Integer age, Professor professor) {
            this.name = name;
            this.age = age;
            this.professor = professor;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Professor getProfessor() {
            return professor;
        }
    
        public void setProfessor(Professor professor) {
            this.professor = professor;
        }
    
        public Object clone() {
    
            Student o = null;
            try {
                o = (Student) super.clone();
            } catch (CloneNotSupportedException e) {
                System.out.println(e.toString());
            }
            //实现深复制
            o.professor = (Professor) professor.clone();
            return o;
        }
    }

package cn.itcast.demo8;
    
    public class Test {
    	public static void main(String[] args) {
    		Professor p = new Professor("wangwu", 50);
            Student s1 = new Student("xiaoming", 20, p);
            Student s2 = (Student) s1.clone();
            s2.getProfessor().setName("xiaowangwu");
            s2.getProfessor().setAge(10);
            System.out.println("s1,name=" + s1.getName() + "," + "age=" + s1.getAge());
            System.out.println("s1,name=" + s1.getProfessor().getName()
                    + "," + "age=" + s1.getProfessor().getAge());
            System.out.println("s2,name=" + s2.getName() + "," + "age=" + s2.getAge());
            System.out.println("s2,name=" + s2.getProfessor().getName()
                    + "," + "age=" + s2.getProfessor().getAge());
    	}
    	
    }

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