使用map惯用的Java 8流？

这个问题已经在这里有了答案：            >            Java stream “forEach” but not consuming stream                                    1个
我真正喜欢的Ruby功能之一是ability to tap into call chains.它提供了一种调试管道中正在发生的事情的简便方法.我用地图模拟了水龙头：

/** Searches recursively and returns the path to the dir that has a file with given extension,
 *  null otherwise.
 * Returns the given dir if it has a file with given extension.
 * @param dir Path to the start folder
 * @param ext String denotes the Traditional extension of a file, e.g. "*.gz"
 * @return {@linkplain Path} of the folder containing such a file, null otherwise
 */
static Path getFolderWithFilesHavingExtension(Path dir, String ext) {
    Objects.requireNonNull(dir); // ignore the return value
    Objects.requireNonNull(ext); // ignore the return value
    try {
        Optional<Path> op = Files.walk(dir, 10).map((t) -> {
            System.out.println("tap: " + t.endsWith(ext));
            System.out.println("tap: " + t.toString().endsWith(ext));
            return t;
        }).filter(p -> p.toString().endsWith(ext)).limit(1).findFirst();
        if (op.isPresent())
            return op.get().getParent();
    } catch (IOException e) {
        return null; // squelching the exception is okay? //Todo
    }
    return null; // no such files found
}

这实际上帮助我修复了一个错误,该错误是我在执行Path :: endsWith而不是String :: endsWith来查看文件名是否以特定扩展名结尾.

在Java 8中是否有更好的(惯用的)方法？

解决方法:

您可以使用.peek(System.out :: println)或.peek(t->“ tap：” t.endsWith(ext))