Question

// shallow copy example
public class a
{
    public static void main(String[] args) throws CloneNotSupportedException
    {
        b x = new b(2);
        System.out.println(x.i[0]); // previous value for object x
        System.out.println(x.k);
        b y =(b)x.clone(); // y shallow clone of object x
        y.i[0] = 10; y.k = 999; // changed values in object y
        System.out.println(y.i[0]); // values of y after change
        System.out.println(y.k);

        System.out.println(x.i[0]); // values of x after change     
        System.out.println(x.k);
        System.out.println(x.getClass() == y.getClass()); // both objects belong to same class
        System.out.println(x == y); // both objects are different, they are not the same
    }
}

class b implements Cloneable
{
    public int i[] = new int[1];
    int k;

    public Object clone() throws CloneNotSupportedException
    {
        return super.clone();
    }

    b(int j)
    {
        super();
        i[0] = j;
        k = j + 2;
    }
}

/*output

2
4
10
999
10
4
true 
false
*/
//*********************************************************************
//deep copy example

public class a
{     
    public static void main(String[] args) throws CloneNotSupportedException 
    {  
        b x = new b(2);
        System.out.println(x.i[0]); // object x values before change
        System.out.println(x.k);

        b y = (b)x.clone(); // deep clone y of object x

        System.out.println(y.i[0]); // values of object y
        System.out.println(y.k);

        System.out.println(x.i[0]); // values of object x after changing the values of the members in object y in clone method  
        System.out.println(x.k);
        System.out.println(x.getClass() == y.getClass());
        System.out.println(x==y);
    }
}

class b implements Cloneable
{
    public int i[] = new int[1];
    int k;

    public Object clone()throws CloneNotSupportedException
    {
        b t = new b(6);
        return t;
    }

    b(int j)
    {
        i[0] = j;
        k = j+2;
    }
}

/*

2
4
6
8
2
4
true 
false
*/

我已经写过这些例子，请看我是否遗漏了任何东西。我必须给出一个关于它的演示，并希望它尽可能简单。如果我能让它变得更简单，请告诉我。我提供了引号，只要它们改变了值或对象被克隆。

Answer 1

演示的黄金提示：使用有意义的类名和变量名，并使示例更具体。例如，使用Book类和Author类

public class Book{
  private String title;
  private Author author;
...
}
public class Author{
  private String name;
  ...
}

使用getter / setter（或公共字段），您可以对Book实例进行深度/浅层克隆，并说明更改Author名称时的更改。与您所做的完全相同，但更容易告诉观众，并且观众更容易遵循，因为每个人都知道书籍和作者是什么，并且不需要查看代码来遵循您的解释

java中浅层和深层复制演示的示例

1 个答案: