Java 接口实现对 [英] Java Interface-Implementation Pair

问题描述

是否有为接口方法创建默认实现的首选方法或样式?假设我有一个常用的界面，在 90% 的情况下，我想要的功能是相同的.

Is there a preferred method or style of creating a default implementation for interface methods? Suppose I had a commonly used interface where in 90% of the cases the functionality I wanted was identical.

我的第一直觉是用静态方法创建一个具体的类.当我需要默认功能时，我会将功能委托给静态方法.

My first instinct is to create a concrete class with static methods. I would then delegate the functionality to the static methods when I want the default functionality.

这是一个简单的例子:

界面

public interface StuffDoer{
    public abstract void doStuff();
}

方法的具体实现

public class ConcreteStuffDoer{
    public static void  doStuff(){
        dosomestuff...
    }
}

使用默认功能的具体实现

Concrete Implementation using default functionality

public class MyClass implements StuffDoer{
    public void  doStuff(){
        ConcreteSuffDoer.doStuff();        
    } 
}

这里有更好的方法吗?

编辑

在看到一些提议的解决方案后，我想我应该更清楚我的意图.本质上，我试图解决不允许多重继承的 Java.另外要明确的是，我并不是要声明 Java 是否应该允许多重继承.我只是在寻找为实现接口的类创建默认方法实现的最佳方法.

After seeing a few of the proposed solutions I think I should be more clear about my intent. Essentially I am trying to work around Java not allowing multiple inheritance. Also to be clear I am not trying to make a statement about whether or not Java should allow multiple inheritance. I am just looking for the best way to create a default method implementation for classes implementing an interface.

推荐答案

这是我会采取的方法:

public interface MyInterface {

      MyInterface DEFAULT = new MyDefaultImplementation();

      public static class MyDefaultImplemenation implements MyInterface {
      }
 }

当然，MyDefaultImplementation 可能需要是私有的，或者它自己的顶级类，这取决于什么是有意义的.

Of course, the MyDefaultImplementation may need to be private, or its own top level class, depending on what makes sense.

然后您可以在您的实现中包含以下内容:

You can then have the following in your implementations:

 public class MyClass implements MyInterface {
        @Override
        public int someInterfaceMethod(String param) {
             return DEFAULT.someInterfaceMethod(param);
        }
  }

与存在于其他地方但未被接口引用的默认实现类相比，它具有更多的自我记录性，并且最终更灵活.有了这个，你可以做一些事情，比如在需要时将默认实现作为方法参数传递(静态方法无法做到这一点).

Its a bit more self-documenting, and ultimately more flexible, than a default implementation class that exists elsewhere but is not referenced by the interface. With this you can do things like just pass the default implementation as a method parameter when required (which you cannot do with the static methods).

当然，以上仅在不涉及状态的情况下才有效.

Of course, the above only works if there is no state involved.

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