Java forEach循环
Java提供了一种新的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。
此方法采用单个参数，它是一个功能接口。因此，您可以将lambda表达式作为参数传递。
可迭代接口中的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
除了forEach()方法，Java还提供了另一种forEachOrdered()方法。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
