所有静态方法还是单个实例? [英] All static methods or a single instance?

问题描述

有时候，由于集合的缘故，我想出了一个类的单个实例就足够了的情况.一个例子就是我的Decoder类:

Sometimes, I come up with situations where a single instance of a class is enough, thanks to collections. An example would be my Decoder class:

public class Decoder
{

    private static final Decoder instance = new Decoder();
    private final HashMap<Client, State> states = new HashMap<Client, State>();

    private Decoder()
    {

    }

    public Packet decode(Client client, ByteBuffer data)
    {
            return null;
    }
}

但是我在想，为什么不做它，使它看起来像这样:

But I was thinking, why not just make it so it looks something like:

public class Decoder
{

    private static final HashMap<Client, State> states = new HashMap<Client, State>();

    public static Packet decode(Client client, ByteBuffer data)
    {
            return null;
    }
}

两种设计都可以有效地完成相同的任务.两者之间有什么实际区别吗?我什么时候可以使用另一个?谢谢.

Both designs effectively accomplish the same thing. Is there any practical difference in the two? When would I use one over the other? Thanks.

推荐答案

我会使用所有静态方法，除非您看到需要实现一个接口，例如这样您就可以模拟或替换您的实例.

I would use all static methods, unless you see the need to implement an interface e.g. so you can mock out or replace your instance.

public enum Decoder implements IDecoder {
    INSTANCE;

    private final Map<Client, State> states = new HashMap<Client, State>();

    public Packet decode(Client client, ByteBuffer data) {
            return null;
    }
}

或

public enum Decoder {;
    private static final Map<Client, State> states = new HashMap<Client, State>();

    public static Packet decode(Client client, ByteBuffer data) {
            return null;
    }
}

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