Example of Directory Lister

package com.darwinsys;
 
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
 
import java.io.File;
 
/**
 * DirTree - directory lister, like UNIX ls or DOS and VMS dir
 * 
 * @author Ian Darwin, http://www.darwinsys.com/
 * @version $Id: DirTree.java,v 1.4 2004/02/09 03:33:47 ian Exp $
 */
public class DirTree {
    /** Main program */
    public static void main(String[] argv) {
	DirTree dt = new DirTree();
	if (argv.length == 0)
	    dt.doDir(".");
	else
	    for (int i = 0; i < argv.length; i++)
		dt.doDir(argv[i]);
    }
 
    /** doDir - handle one filesystem object by name */
    private void doDir(String s) {
	File f = new File(s);
	if (!f.exists()) {
	    System.out.println(s + " does not exist");
	    return;
	}
	if (f.isFile())
	    doFile(f);
	else if (f.isDirectory()) {
	    System.out.println("d " + f.getPath());
	    String objects[] = f.list();
 
	    for (int i = 0; i < objects.length; i++)
		doDir(s + f.separator + objects[i]);
	} else
	    System.err.println("Unknown: " + s);
    }
 
    /** doFile - process one regular file. */
    private static void doFile(File f) {
	System.out.println("f " + f.getPath());
    }
}