如何不通过引用将元素从 ArrayList 复制到另一个? [英] How to copy elements from an ArrayList to another one NOT by reference?

问题描述

我正在尝试将每个元素从一个 ArrayList (av) 复制到另一个 (copia).问题是它们是通过引用复制的，所以每当我对原始副本进行任何更改时，副本也会被修改.当然，这种行为是不想要的.这个方法应该怎么写?

I'm trying to copy each element from one ArrayList (av) to another one (copia). The thing is that they're copied by reference, so whenever I make any changes in the original one, the copy is modified as well. Of course, this behavior is not wanted. How should I write this method?

public void copiarArrayList(ArrayList<Articulo_Venta> copia, ArrayList<Articulo_Venta> av){
    copia.clear();
    for (int i = 0; i < av.size(); i++) {
        copia.add(av.get(i));
    }
}

Articulo_Venta 具有以下字段:

Articulo_Venta has these fields:

int codigo;
String nombre;
float cantidad;

PS:我也试过下一个:

PS: I also tried the next:

copia = new ArrayList<Articulo_Venta>(av);

但它的元素仍然指向原始的 ArrayList.

but it still has its elements pointing to the original ArrayList.

推荐答案

你想要的是深拷贝.如果您的对象仅包含原始对象，您可以使用 clone()，否则最好的方法是手动执行:-

What you want is the deep copy. If your object contains only primitive you could use clone(), otherwise best way is to do manually:-

在您的 Articulo_Venta 类中创建一个构造函数，它接受另一个 Articulo_Venta 对象并初始化成员变量.

Make a constructor in your Articulo_Venta class which takes another Articulo_Venta object and initializes member variables.

然后将代码更改为:-

public void copiarArrayList(ArrayList<Articulo_Venta> copia, ArrayList<Articulo_Venta> av){
        copia.clear();
        for (int i = 0; i < av.size(); i++) {
            copia.add(new Articulo_Venta(av.get(i)));
        }

另请阅读这里 - how-do-you-make-a-deep-copy-of-an-object-in-java

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