java8 - 使用Function接口替换Consumer或Supplier [英] java8 - use Function interface to replace Consumer or Supplier

问题描述

由于Consumer / Supplier / Predicate / UnaryOperator只是Function的一个特例，我如何用Function替换这些界面？

Since that Consumer/Supplier/Predicate/UnaryOperator is just a special case of Function, how can I replace these interfacces with Function?

T - > Function - > R

T -> Function -> R

T - >消费者 - > null

T -> Consumer -> null

null - >供应商 - > T

null -> Supplier -> T

T - > Predicate - > boolean

T -> Predicate -> boolean

T - > UnaryOperator - > T

T -> UnaryOperator -> T

null& boolean只是T的一个特例。所以我用函数代替谓词和UnaryOperator写了两个案例。

null & boolean is just a special case for T. So I write two cases using Function to replace Predicate and UnaryOperator.

例如：

private static void replacePredicate() {
    Function<String, Boolean> func = x -> x.startsWith("a");
    Predicate<String> pre = x -> x.startsWith("a");

    System.out.println(func.apply("ape"));
    System.out.println(pre.test("ape"));
}

private static void replaceUnaryOperator() {
    Function<Integer, Integer> func = x -> x * 2;
    UnaryOperator<Integer> uo = x -> x * 2;

    System.out.println(func.apply(6));
    System.out.println(uo.apply(6));
}

但我怎么能用Function来代替Consumer或Suppler？例如，我想替换Consumer，但代码如 Function< String，null> func = x - > System.out.println（x）; 是非法的。

But how could I use Function to replace Consumer or Suppler? For example, I want to replace Consumer, but code like Function<String, null> func = x -> System.out.println(x); is illegal.

任何建议都将非常感谢〜

Any suggestion will be greatly appreciated~

推荐答案

消费者< T> 可以被视为功能< T，Void> ; 。 供应商< T> 可以被视为功能< Void，T> 。您必须从作为函数编写的消费者中返回null，并从供应商处获取（并忽略）作为函数的Void作为参数。

A Consumer<T> can be viewed as a Function<T, Void>. A Supplier<T> can be viewed as a Function<Void, T>. You'll have to return null from your consumer written as a function, and take (and ignore) a Void as argument from your supplier written as a function.

不确定不过，我明白了这一点。

Not sure I get the point of this, though.

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