Java forEach循环 _Java新特性

本文概述

迭代接口中的forEach()签名
Java Stream forEachOrdered()方法

【Java forEach循环】Java提供了一个新的forEach()方法来迭代元素。它在Iterable和Stream接口中定义。这是Iterable接口中定义的默认方法。扩展Iterable接口的集合类可以使用forEach循环来迭代元素。
该方法采用单个参数, 该参数是功能接口。因此, 你可以将lambda表达式作为参数传递。
迭代接口中的forEach()签名

default void forEach(Consumer< super T> action)

Java 8 forEach()示例1

import java.util.ArrayList; import java.util.List; public class ForEachExample { public static void main(String[] args) { List< String> gamesList = new ArrayList< String> (); gamesList.add("Football"); gamesList.add("Cricket"); gamesList.add("Chess"); gamesList.add("Hocky"); System.out.println("------------Iterating by passing lambda expression--------------"); gamesList.forEach(games -> System.out.println(games)); } }

输出：

------------Iterating by passing lambda expression-------------- Football Cricket Chess Hocky

Java 8 forEach()示例2

import java.util.ArrayList; import java.util.List; public class ForEachExample { public static void main(String[] args) { List< String> gamesList = new ArrayList< String> (); gamesList.add("Football"); gamesList.add("Cricket"); gamesList.add("Chess"); gamesList.add("Hocky"); System.out.println("------------Iterating by passing method reference---------------"); gamesList.forEach(System.out::println); } }

输出：

------------Iterating by passing method reference--------------- Football Cricket Chess Hocky

Java Stream forEachOrdered()方法Java与forEach()方法一起, 为EachOrdered()提供了另一种方法。它用于按流指定的顺序迭代元素。
Singnature：

void forEachOrdered(Consumer< ? super T> action)

Java Stream forEachOrdered()方法示例

import java.util.ArrayList; import java.util.List; public class ForEachOrderedExample { public static void main(String[] args) { List< String> gamesList = new ArrayList< String> (); gamesList.add("Football"); gamesList.add("Cricket"); gamesList.add("Chess"); gamesList.add("Hocky"); System.out.println("------------Iterating by passing lambda expression---------------"); gamesList.stream().forEachOrdered(games -> System.out.println(games)); System.out.println("------------Iterating by passing method reference---------------"); gamesList.stream().forEachOrdered(System.out::println); }}

输出：

------------Iterating by passing lambda expression--------------- Football Cricket Chess Hocky ------------Iterating by passing method reference--------------- Football Cricket Chess Hocky