Question

我受了很久的苦

告诉我下面的代码是否克隆了?

class A
{  
 int i;
    int j;  
    String str;  
    A()  
    {  
      i=10;  
      j=30;  
      str="Hello";  
    }  
    A(A a)  
   {  
      this.i=a.i;  
      this.j=a.j;  
      this.str=a.str;  
   }  
}  
class B
{  
   public static void main(String args[])  
   {
      A a  = new A();  
      A a1 = new A(a);
      /* I want to make clone like this. */  
      } 
}

when I run this code and when I print hashcode of a and a1, they are different. But some of my friends say that this is not the correct way to make a clone. You have to implement the Cloneable interface, is that really necessary? In my opinion, it can be a good approach if I want to make a deep copy even in case of derived reference variable. Thank you.

Answer 1

您需要安装可克隆界面才能克隆对象。您所执行的是一个复制构建器。复制构建器比执行可克隆更可取。

您复制对象与被复制对象有不同的散列码/等值, 原因是您没有翻过散列码或等同 A类中的函数, 所以它检查身份, 而不是只检查平等( exact 相同对象, 而不是具有相同值的对象) 。通过压过散列码/ 等, 您可以使您的类比较其属性的值。

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