How to list all files in a given directory?

Question

How to list all the files in a given directory?

Answer 1

A possible recursive algorithm for printing all the files in a directory and its subdirectories is:
Print the name of the directory
for each file in the directory:
if the file is a directory:
Print its contents recursively
else
Print the name of the file.
Directory "games"
blackbox
Directory "CardGames"
cribbage
euchre
tetris
The Solution
This program lists the contents of a directory specified by
the user. The contents of subdirectories are also listed,
up to any level of nesting. Indentation is used to show
the level of nesting.
The user is asked to type in a directory name.
If the name entered by the user is not a directory, a
message is printed and the program ends.
import java.io.*;
public class RecursiveDirectoryList {
public static void main(String[] args) {
String directoryName; // Directory name entered by the user.
File directory; // File object referring to the directory.
TextIO.put("Enter a directory name: ");
directoryName = TextIO.getln().trim();
directory = new File(directoryName);
if (directory.isDirectory() == false) {
// Program needs a directory name. Print an error message.
if (directory.exists() == false)
TextIO.putln("There is no such directory!");
else
TextIO.putln("That file is not a directory.");
else {
// List the contents of directory, with no indentation
// at the top level.
listContents( directory, "" );
} // end main()
static void listContents(File dir, String indent) {
// A recursive subroutine that lists the contents of
// the directory dir, including the contents of its
// subdirectories to any level of nesting. It is assumed
// that dir is in fact a directory. The indent parameter
// is a string of blanks that is prepended to each item in
// the listing. It grows in length with each increase in
// the level of directory nesting.
String[] files; // List of names of files in the directory.
TextIO.putln(indent + "Directory \"" + dir.getName() + "\":");
indent += " "; // Increase the indentation for listing the contents.
files = dir.list();
for (int i = 0; i < files.length; i++) {
// If the file is a directory, list its contents
// recursively. Otherwise, just print its name.
File f = new File(dir, files);
if (f.isDirectory())
listContents(f, indent);
else
TextIO.putln(indent + files[i]);
} // end listContents()
} // end class RecursiveDirectoryList
Cheers,
Kosh!