java多个构造方法,Java中构造函数中的多个可选参数

博主探讨了在类中拥有大量可选实例变量时，如何避免创建无数构造函数的困境。他们遇到了需要为每个可能的组合创建构造函数的情况，这导致了极高的组合数量。为了解决这个问题，博主建议采用建造者模式，这是一种更优雅的设计模式，可以更好地管理和维护代码，减少构造函数的数量。

This is something I've encountered a few times and haven't been able to find a satisfying answer yet. This seems pretty stupid, but after googling this for a while I couldn't come up with something good.

Let's say I have a class with 20 instance variables, each of which is optional (will be initialized or not).

Now I want my constructor(s) to handle all the cases, in case of a few instance variables it's fine and I can just create constructors with different signatures, but here I have 20, so I would need 2^20=1,048,576 constructors to handle all the cases ! That seems ... not very optimal, don't you agree?

So since with this brute force approach I basically have to construct 2^n constructors, where n is the number of instance variables, I want to find a better way to do it.

I've seen a couple solutions for this problem, but I believe they all on assumptions on the data, but in my case each of these variables can be initialized or not at random, I have no way of knowing that before initialization.

I'm looking for some design patterns or ideas that I could apply to make my code a bit more ... maintainable (no don't worry I didn't create 1M+ constructors :)

Thanks.

解决方案

Try the Builder pattern: