顺利使用Function< A，R>从Scala的Java接口？ [英] Smooth way of using Function<A, R> java interface from scala?

问题描述

在工作中，大多数人使用Java，而我正在与Scala合作。我们决定在一个将用Java编写的库中收集一些通用的类。现在我想添加一些伪函数编程到库中，看看下面的内容：

Here at work most people use Java, while I am working with Scala. We have decided to gather some common classes in an library which will be written in Java. Now I want to add some pseudo-functional programming to the library, take a look at the following:

java：

public interface Func<A, R> {
    public R f(a A);
}

public AClass {
    public <R> ArrayList<R> myMethod(
                             Func<String, R> func
    ) {
        // ...
    }
}

在java中的用法：

AClass ac = new AClass();
ArrayList<String> al = ac.myMethod(
                            new Func<String, String> (
                                public String f(String s) {
                                    return s + "!";
                                }
                            })

以上并不完全是退出（从scala的角度来看更像是令人生畏的）。有什么办法可以召唤一些scala魔法，以便能够在scala中做如下的事情：

The above is not exactly exiting (more like daunting actually, from a scala perspective). Is there any way to summon some scala magic to be able to do something like the following in scala:

var ac = new ACLass
var al = ac.myMethod(str => str + "!")             // alternative 1
al = ac.myMethod { case: str:String => str + "!" } // alternative 2

我混淆了一段时间的implicits，但无法将事情整理出来= P。

I messed around with implicits for a while but couldn't get things sorted out =P.

推荐答案

隐式转换：

With implicit conversions:

object FuncConversions {
  implicit def func2function[A,R]( fn: (A) => R ) =
    new Func[A,R] {
      def f(a: A) = fn(a)
    }
}

不要忘记在您的作用域中导入转换：

Don't forget to import the conversion in your scope:

import FuncConversions._

您也可以实现相反的转换。

You can also implement the opposite conversion.

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