目录和文件时磁盘树形结构中最基本的组成单元，Java用File类来统一表示它们，

* 并通过File类来完成目录和文件的创建、删除、查询等操作。

* 手工创建d:\test文件夹，编写一个Java程序，

* 遍历“d:\test”文件夹，如果文件夹为空，则创建一个新文件a.txt，并把此文件的名称打印出来；

* 如果文件夹不为空，那么将该文件夹下的文件和目录遍历以后，

* 按照目录和文件类型，分类把目录名称和文件名分称打印出来。-Basic constituent units of disk tree structure of directories and files, Java File class unified representation,* and through the File class to complete the creation of directories and files, delete, query and other operations.* Manually create d: \ the test folder, write a Java program, the* traverse " d: \ test"　folder, if the folder is empty, create a new file a.txt and print out the name of this file * If the folder is not empty, then after the folder under the file and directory traversal* in accordance with the directory and file type, classified directory name and file birthright said print it out.