Supplier接口

package java.util.function;/** * Represents a supplier of results. * * <p>There is no requirement that a new or distinct result be returned each * time the supplier is invoked. * * <p>This is a <a href="package-summary.html" rel="external nofollow" rel="external nofollow" >functional interface</a> * whose functional method is {@link #get()}. * * @param <T> the type of results supplied by this supplier * * @since 1.8 */@FunctionalInterfacepublic interface Supplier<T> { /** * Gets a result. * * @return a result */ T get();}

supplier接口只有一个抽象方法get(),通过get方法产生一个T类型实例。

实例：

package me.yanand;import java.util.function.Supplier;public class TestSupplier { public static void main(String[] args) { Supplier<Apple> appleSupplier = Apple::new; System.out.println("--------"); appleSupplier.get(); }}class Apple{ public Apple() { System.out.println("创建实例"); }}

Consumer接口

package java.util.function;import java.util.Objects;/** * Represents an operation that accepts a single input argument and returns no * result. Unlike most other functional interfaces, {@code Consumer} is expected * to operate via side-effects. * * <p>This is a <a href="package-summary.html" rel="external nofollow" rel="external nofollow" >functional interface</a> * whose functional method is {@link #accept(Object)}. * * @param <T> the type of the input to the operation * * @since 1.8 */@FunctionalInterfacepublic interface Consumer<T> { /** * Performs this operation on the given argument. * * @param t the input argument */ void accept(T t); /** * Returns a composed {@code Consumer} that performs, in sequence, this * operation followed by the {@code after} operation. If performing either * operation throws an exception, it is relayed to the caller of the * composed operation. If performing this operation throws an exception, * the {@code after} operation will not be performed. * * @param after the operation to perform after this operation * @return a composed {@code Consumer} that performs in sequence this * operation followed by the {@code after} operation * @throws NullPointerException if {@code after} is null */ default Consumer<T> andThen(Consumer<? super T> after) { Objects.requireNonNull(after); return (T t) -> { accept(t); after.accept(t); }; }}

一个抽象方法accept(T t)定义了要执行的具体操作；注意看andThen方法，接收Consumer<? super T>类型参数，返回一个lambda表达式，此表达式定义了新的执行过程，先执行当前Consumer实例的accept方法，再执行入参传进来的Consumer实例的accept方法，这两个accept方法接收都是相同的入参t。

实例：

package me.yanand;import java.util.function.Consumer;public class TestConsumer { public static void main(String[] args) { Consumer<Integer> consumer = (t) -> { System.out.println(t*3); }; Consumer<Integer> consumerAfter = (s) -> { System.out.println("之后执行："+s); }; consumer.andThen(consumerAfter).accept(5); }}

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