java:从另一个类获取私有变量，而无需设置getter [英] java: get private variable from another class, without setting a getter

问题描述

我不允许更改类A，但是我需要获取'a'的值(在构造函数中设置).谁能告诉我该怎么做?其他所有解决方案似乎都建议在A类中使用一种吸气剂.我不允许以任何方式对A类进行更改，不得对公众进行更改，等等.魔术必须在B类中发生.

I am not allowed to alter class A, but i need to get the value of 'a'(set in the constructor). Can anyone tell me how to do that? Every other solution seems to propose a getter in class A. I am not allowed to make changes to class A in any way, no changing to public etc. The magic has to happen in class B.

public class A{
    private int a;
    public A(int x){
        a = x * 10;
    }
}

public class B{
    public B(int x){
        A instA = new A(x);
    }

    public int geta(){
        ???
    } 
}

PS:张贴了这个问题，因为每个类似的问题都通过更改A类来回答，而我却不允许这样做.但是由于似乎只有反思，所以可以解决这个问题.谢谢伙计们.

PS: Posted this question, because every similar question was answered with altering class A, whereas i am not allowed to do so. But since there seems to be only reflection, this question can be closed. Thanks guys and gals.

推荐答案

这是 private 字段的全部要点；在封闭类的范围之外无法访问它们.

That is the whole point of private fields; they are not accessible outside the scope of the enclosing class.

您有以下选择:

1. 更改该类以提供一个吸气剂
2. 更改总体设计，以使其不需要该值；或寻找另一种方法使这两个类都可以使用
3. 不推荐:使用反射及其在运行时覆盖私有"保护的功能

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