Java8 中是否有标准化的通用功能接口？

Question

我想知道是否以及在哪里有人定义了一组通用功能接口来简化和标准化 lambda 的使用。我来自核心库完成工作的 C#。

我读到了 "BiFunction"，发现它很笨拙。特别是当扩展到 TriFunction 等时

我得出以下结论：

public interface FI {
@FunctionalInterface
public interface Action<T> {
    void invoke(T arg1);
}
@FunctionalInterface
public interface Function0<TResult> {
    TResult invoke();
}
@FunctionalInterface
public interface Function1<Targ1, TResult> {
    TResult invoke(Targ1 arg1);
}
@FunctionalInterface
public interface Function2<Targ1, Targ2, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2);
}
@FunctionalInterface
public interface Function3<Targ1, Targ2, Targ3, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3);
}
@FunctionalInterface
public interface Function4<Targ1, Targ2, Targ3, Targ4, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4);
}
@FunctionalInterface
public interface Function5<Targ1, Targ2, Targ3, Targ4, Targ5, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5);
}
@FunctionalInterface
public interface Function6<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6);
}
@FunctionalInterface
public interface Function7<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7);
}
@FunctionalInterface
public interface Function8<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, Targ8, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7, Targ8 atg8);
}
@FunctionalInterface
public interface Function9<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, Targ8, Targ9, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7, Targ8 atg8, Targ9 arg9);
}
@FunctionalInterface
public interface Function10<Targ1, Targ2, Targ3, Targ4, Targ5, Targ6, Targ7, Targ8, Targ9, Targ10, TResult> {
    TResult invoke(Targ1 arg1, Targ2 arg2, Targ3 arg3, Targ4 arg4, Targ5 arg5, Targ6 arg6, Targ7 arg7, Targ8 atg8, Targ9 arg9, Targ10 arg10);
}

}

Answer 1

在Java8中官方只存在4种Functions。

  Consumer: Void function
  Function: receive argument return argument
  BiFunction: Receive 2 arguments return argument
  Predicate: receive argument return boolean

在这里你可以看到一些关于它的例子。

https://github.com/politrons/reactive/blob/master/src/test/java/stream/Functions.java

Answer 2

您将在 java.util.function 包中找到最接近的类似物：

interface Function<T,R> { R apply(T t) }

interface Consumer<T> { void accept(T t) }

interface BiFunction<T,U,R> { R apply(T t, U u) }

等您可以定义自己的，或者您可以在 Google Guava 或其他库中找到一些。

Answer 3

javaslang[1]提供Function0-Function8甚至CheckedFunction0-CheckedFunction8。它们甚至提供额外的功能，如 'memoization' 和 'currying'。

http://javaslang.io

Java8 中是否有标准化的通用功能接口？

Are there standardized generic functional interfaces in Java8?

java

functional-interface