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

问题描述

是否有一种首选的方法或风格来创建界面方法的默认实现？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.

我的第一本能就是用静态方法创建一个具体的类。然后，当我想要默认功能时，我将把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：

接口

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

具体实施方法

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

在看到一些提出的解决方案后，我想我应该更加清楚我的意图本质上我正在努力解决Java不允许多重继承。另外要清楚，我不是想就Java是否允许多重继承作出声明。我只是寻找为实现接口的类创建默认方法实现的最佳方式。

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

这是我要采取的方法：

public interface MyInterface {

      MyInterface DEFAULT = new MyDefaultImplementation();

      public static class MyDefaultImplemenation implements MyInterface {
      }
 }

当然，MyDefaultImplementation可能需要是私有的，或者是自己的顶级类，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，您可以将以下内容您的实现：

You can then have the following in your implementations:

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

它有更多的自我记录，最终更多比在其他地方存在但不被接口引用的默认实现类更灵活。有了这个，你可以做任何事情，只需要传递默认实现作为一个方法参数，当需要（你不能用静态方法）。

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，上面只有如果没有涉及国家的工作。

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

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