Java 函數接口Functional Interface

創建: 2020/11/27

完成: 2020/11/27

 

https://docs.oracle.com/javase/8/docs/api/java/util/function/package-summary.html

Functional interfaces provide target types for lambda expressions and method references.

函數接口提供lambda表達式和函數變量的數據類型

java.util.function.*

主要接口
Runnable	java.lang 常用於Thread public interface Runnable { public abstract void run(); }
Supplier<T>	沒有參數返回一個值 public interface Supplier<T> { public abstract T get(); }
Consumer<T>	有一個參數沒有返回值 public interface Consumer<T> { void accept<T t>; default Consumer<T> andThen(ConSumer<? super T> after) { Object.requireNoNull(requireNonNull); return (T t) -> { accept(t); after.accept(t); }; } }
Function<T, R>	有一個參數一個返回值 public interface Function<T, R> { R apply(T t); default <V> Function<V, R> compose(Function<? super V, ? extends T> before) { Objects.requireNonNull(before); return (V v) -> apply(before.apply(v)); } default <V> Function<T, V> andThen(Function<? super R, ? extends V> after) { Objects.requireNonNull(after); return (T t) -> after.apply(apply(t)); } static <T> Function<T, T> identity() { return t -> t; } }
Prediable<T>	有一個參數返回一個boolean public interface Predicate<T> { boolean test(T t); default Predicate<T> and(Predicate<? super T> other) { Objects.requireNonNull(other); return (t) -> test(t) && other.test(t); } default Predicate<T> negate() { return (t) -> !test(t); } default Predicate<T> or(Predicate<? super T> other) { Objects.requireNonNull(other); return (t) -> test(t) || other.test(t); } static <T> Predicate<T> isEqual(Object targetRef) { return (null == targetRef) ? Objects::isNull : object -> targetRef.equals(object); } }