Java对象参考 [英] Java Object reference

问题描述

这与另一个类实例变量返回的ArrayList的使用有关.

This is regarding the usage of ArrayList returned by another class instance variable.

Class A {

    //assigned list of string to it.
    private List < String > newAl;
    //returns the list
    public List < String > getList() {
        return newA1;
    }
}

Class Test {

    public void go() {
        List < String > list = a.getList();
        list.add("");
    }

}

在Test类中，当我检索列表并操作列表时，由于引用，A类列表也被操纵.如果A是第三方代码的一部分.如何在Test类中更正我的代码，以便原始对象会不会受到影响?

In the Test class when i retreive list and manipulate the list.Because of the reference ,class A list also got manipulated.If A is part of third party code.How do I correct my code in Test class so that original object wouldnt be affected?

推荐答案

The ArrayList constructor takes a Collection so you can use that:

List<String> list = new ArrayList(a.getList());

我认为最好这样做，但是根据您的工作，您可能需要在吸气剂中构造新的List.这也有助于隐藏类型.

I think it's better to do it like this, but depending on what you're doing, you may want to construct the new List in the getter. That also helps type hiding.

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