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).事实是，它们是通过引用复制的，因此，只要我对原始副本进行了任何更改，副本也将被修改.当然，不需要这种行为.我应该怎么写这个方法?

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:我也尝试了下一个:

PS: I also tried the next:

copia = new ArrayList<Articulo_Venta>(av);

但它仍然具有指向原始ArrayList的元素.

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

推荐答案

您想要的是深层副本.如果您的对象仅包含原始对象，则可以使用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Articulo_Venta类中构造一个构造函数，该构造函数采用另一个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)));
        }

也请在这里阅读- how您是否在Java中制作了对象的深层副本

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