I/O flow in the file class common methods (2)

5, folder Related:
1) staic file[] Listroots () lists all the root directories (the letter for All systems in window)
Example:

File[] roots = File.listroots (); Lists all the root for
    (file file  : Roots) {
        System.out.println (file);
    }

2 list () returns the file or directory name in the directory containing the hidden files. This action returns null for the file.
Example:

string[] FileNames = File.list (); 
/* Stores all child file names and subfolder names below the current folder in a string type array. */For
    (String filename:filenames) {
        System.out.println (fileName);   
    }

3) Listfiles () returns a file or directory object (instance of the file class) in the directory containing hidden files. This action returns null for the file.
Example:

file[] files = file.listfiles (); /* Use a File object description for all subfolders and subfolders below the current folder, and then store the file objects in a file array to return the */for
    (file fileitem:files) {
        System.out.println ("Wennan:" +fileitem.getname ());
    }

4) List (FilenameFilter filter) returns a child file or subdirectory that matches the filter criteria in the current directory. This action returns null for the file.
5) Listfiles (FilenameFilter filter) returns a child file or subdirectory that matches the filter criteria in the current directory. This action returns null for the file.
Example:

The two methods are similar, except that the return value of the list is of type string.