Java中遍历容器主要用for，在JDK 1.8中提供了forEach方法，源码如下：

/** * Performs the given action for each element of the {@code Iterable} * until all elements have been processed or the action throws an * exception. Unless otherwise specified by the implementing class, * actions are performed in the order of iteration (if an iteration order * is specified). Exceptions thrown by the action are relayed to the * caller. * * @implSpec * <p>The default implementation behaves as if: * <pre>{@code * for (T t : this) * action.accept(t); * }</pre> * * @param action The action to be performed for each element * @throws NullPointerException if the specified action is null * @since 1.8 */

default void forEach(Consumer<? super T> action) {
    Objects.requireNonNull(action);
    for (T t : this) {
        action.accept(t);
    }
}

用法：

public class ForEach{
    public static void  main(String[] args) {
        List<String> list = new ArrayList<String>();
        list.add("first");
        list.add("second");
        list.add("third");
        list.add("four");
        list.add("five");

        list.forEach((num)->System.out.println(num));
        return;
    }
}

输出：

first
second
third
four
five