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Java8Supplier接口和Consumer接口的用法

这篇文章主要讲解了Java8 Supplier接口和Consumer接口的用法,内容清晰明了,对此有兴趣的小伙伴可以学习一下,相信大家阅读完之后会有帮助。

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Supplier接口

package java.util.function;
/**
 * Represents a supplier of results.
 *
 * 

There is no requirement that a new or distinct result be returned each * time the supplier is invoked. * *

This is a functional interface * whose functional method is {@link #get()}. * * @param the type of results supplied by this supplier * * @since 1.8 */ @FunctionalInterface public interface Supplier { /** * 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 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.
 *
 * 

This is a functional interface * whose functional method is {@link #accept(Object)}. * * @param the type of the input to the operation * * @since 1.8 */ @FunctionalInterface public interface Consumer { /** * 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 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 consumer = (t) -> {
      System.out.println(t*3);
    };
    Consumer consumerAfter = (s) -> {
      System.out.println("之后执行:"+s);
    };
    consumer.andThen(consumerAfter).accept(5);
  }
}

看完上述内容,是不是对Java8 Supplier接口和Consumer接口的用法有进一步的了解,如果还想学习更多内容,欢迎关注创新互联行业资讯频道。


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