对象克隆

class Money1 {
    double money = 10.0;
}

class Person1 implements Cloneable{
    public String name;
    Money1 m;
    public Person1(String name){
        this.name = name;
        m = new Money1();
    }
    
    
}

public class TestCloneDemo1 {

    public static void main(String[] args) throws Exception {
        /*student s1 = new student(10);
        System.out.println(s1);*/
        Person1 p1 = new Person1("caocao");
        
        Person1 p2 = (Person1)p1.clone();//这里会报错  此时要对clone方法进行重写

class Money1 {
    double money = 10.0;
}

class Person1 {
    public String name;
    Money1 m;
    public Person1(String name){
        this.name = name;
        m = new Money1();
    }
    protected Object clone() throws CloneNotSupportedException {
        //Person重写
        Person1 p = (Person1)super.clone();
        
        return p;
    }
    
}

重写后仍然会报错  这是Person1类没有实现Cloneable这个接口

作用：

class Money1 {
    double money = 10.0;
}

class Person1 implements Cloneable{
    public String name;
    Money1 m;
    public Person1(String name){
        this.name = name;
        m = new Money1();
    }
    protected Object clone() throws CloneNotSupportedException {
        //Person重写
        Person1 p = (Person1)super.clone();//强转  clone（）方法是基类object里面的方法
        
        return p;
    }
    
}

public static void main(String[] args) throws Exception {
        /*student s1 = new student(10);
        System.out.println(s1);*/
        Person1 p1 = new Person1("caocao");
        
        Person1 p2 = (Person1)p1.clone();
        
        
        System.out.println(p1.m.money);
        System.out.println(p2.m.money);
        
        p1.m.money = 1000.0;
        
        System.out.println(p1.m.money);
        System.out.println(p2.m.money);
结果

10.0
10.0
1000.0
1000.0

 

 

改变p2的值p1的值也变了，？？？
只克隆了person对象，并没有克隆Money对象。需要在money类写入clone（）方法

class Money1 implements Cloneable{
    double money = 10.0;
    @Override
    protected Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

class Person1 implements Cloneable{
    public String name;
    Money1 m;
    public Person1(String name){
        this.name = name;
        m = new Money1();
    }
    @Override
    protected Object clone() throws CloneNotSupportedException {
        //Person重写
        Person1 p = (Person1)super.clone();
        p.m = (Money1)this.m.clone();//对当前对象内的引用进行克隆
        return p;
    }
    
}

public class TestCloneDemo1 {

    public static void main(String[] args) throws Exception {
        /*student s1 = new student(10);
        System.out.println(s1);*/
        Person1 p1 = new Person1("caocao");
        
        Person1 p2 = (Person1)p1.clone();
        
        
        System.out.println(p1.m.money);
        System.out.println(p2.m.money);
        
        p1.m.money = 1000.0;
        
        System.out.println(p1.m.money);
        System.out.println(p2.m.money);  
        

    }

}
结果：

10.0
10.0
1000.0
10.0