Directory/File comparison tool using Java.

Hello Everybody,
I have to build a tool for Direcotry/File comparison ( ASCII, TEXT, BYTE ) any format. I am thinking of building with Java for platform independence.
So does anybody have any idea how should I proceed.
I have to be really quick. It would be really nice to start with inputs from Java gurus.
Thanks,
Nanu

Not a very hard thing to do. You'll make heavy use of the java.io.File class, so go off and read the whole API page for it. File is what you'll use to find out if something is a directory and to list a directory.
The first thing to do is probably to sit down and write down exactly what the program's interface should be like, and what exactly it should do in various situations. From your brief problem description here, there are many different ways you could go.

Hi Ernest,
I have to develop commandline interface for this tool, which will take care of all the forms of file I mentioned in my previous post disregarding the time stamp. Also, I have one question, can we convert TEXT file to byte code with java for the comparison purpose?
I am new to this tool and never used one, so if you can provide me with little more description of the ways I can opt for it will be really nice.
Thanks,
Nanu

Here's the doc for something I did in Pascal, first version in DOS about 1987, last version with a nifty GUI. It compares directories and files by timestamps. Comparing files by content would be an interesting addition. See if it gives you any ideas. I'd be happy to talk about the algorithms.
Saxman Software Tools Disk Series Program: TDTwoDir Version: 3.4 10/13/1996 Purpose: Maintain two directories Syntax: TDTWODIR Author: Jim Standley, Saxman Software Language: Borland Delphi Requires: Windows 3.1 or later Overview TDTwoDir may be used to maintain sets of similar files in two directories or on two disks. It lets you move, copy or erase files from either or both directories depending on a set of rules. You name the two directories, which can include drive, path and filespec. You also select one or more of 14 rules about what actions to take. For example, "If a file exists in both directories and the file in Directory 1 is newer, copy it to Directory 2." Then TDTwoDir reads and sorts the directories and goes to work. You can run TDTwoDir in fully automatic mode, prompting mode, or a mode that displays commands instead of doing them. Option Sets All the settings described under Directories, Run Options and Rules below can be saved together as an option set, and reloaded later. An option set can include the directories and filespecs for particular backup or recovery operations, or they can leave these blank for more generic cominations of options. See the action bar menu selection "File" for option sets. As of Version 3.2 the menu options for option sets have been changed to the standard Windows File / New, Save, Save As. New resets all options on screen to the defaults. As of Version 3.3 the options for processing subdirectories are properly saved and loaded. Directories You can enter the two directories by typing them, or you can press the little button to the right of each directory and use standard drive and directory boxes to select directories. You can add a filespec to one or both directories, such as "A:\WORD\*.DOC". If there is no filespec, make sure the directory name ends with a backslash, or the program will think the directory name is a filespec. For example, "C:\WINDOWS" looks like a file to the program. Run Options There are three modes of operation. You can select one via the radio buttons on the window. * Automatic. The program executes commands without pausing. * Prompted. The program displays each command and asks whether or not to execute it. Respond "Y" or "N". * Display only. The program displays each command and waits for any key to be pressed. Commands are displayed only and are not executed. Rules There are 14 rules for actions on files. You can select any or all rules in any combination. If file exists in Directory 1 Only A. Copy from 1 to 2 B. Erase from 1 If file exists in Directory 2 Only C. Copy from 2 to 1 D. Erase from 2 If file exists in both directories And file in Directory 1 is newer E. Copy from 1 to 2 F. Copy from 2 to 1 G. Erase From 1 H. Erase From 2 And file in Directory 2 is newer I. Copy from 1 to 2 J. Copy from 2 to 1 K. Erase From 1 L. Erase From 2 And file dates match M. Erase from 1 N. Erase from 2 You can read these rules out loud. For example, Rule B says "If the file exists in directory 1 only, erase it from directory 1." For any given file or pair of files, only one "if test" will be true, but any number of rules under that test might be selected. Rules are executed in the order you see them, so some combinations are very powerful while others range from ineffective to dangerous. TDTwoDir allows any combination; it does not prevent dumb mistakes. Note that "newer" is based on the date and time you see when you list files with "DIR". If you are comparing files on two computers, perhaps over a LAN or laptop link, make sure their clocks agree! Examples: Say you have a hard disk directory with documents for a particular project. For nightly backup to diskette: Dir 1: C:\PROJECT\*.DOC project directory Dir 2: A:\ compare to all files on A: Rules A - Copy unique files to backup D - Get rid of obsolete files on backup E - Copy updated files to backup Now you do some wild experimental changes to a few files and make a mess of things. You want to restore from backup, but only the files you have changed. Dir 1: C:\PROJECT\*.DOC Dir 2: A:\ Rules B - Get rid of any unique files F - Replace changed file with backup In those two examples, deleting the unique files might not be desirable. They just show how the program works. Here's a bad combination. This release of TDTwoDir does not attempt to detect such things. Rules E - Copy modified files to backup H - Erase from backup Another bad idea would be running TDTwoDir on only one directory by giving the same directory name twice. Any delete command would delete the ONLY copy, and attempts to copy a file onto itself will not work. Subdirectories As of Version 3.3 the options to process subdirectories and create directories are enabled. The program will create directories as needed to copy files from the source to the target. It will duplicate empty directories. It will not (yet) delete directories. On the file disposition window, directory names end with a back slash. When "copy" operations are executed, the program will create new subdirectories only if the target does not exist. If a copy operation is done because one directory is newer than the other, the program will actually do nothing. Parameters As of version 3.2 you can specify fileids for one or more option set files on the command line. In Windows 3.x you have to do this in the program properties in Program Manager. With Windows NT you can launch window programs from the command line, so you can also do it from a DOS prompt or batch file. If any fileids are given, the program processes them one at a time and quits after processing all of them. The search path for files is not good yet; give the full drive & path on the command line for now.

Given such a requirement (which may be bogus), I would be focusing on what I believe is the most difficult part: creating an algorithm that determines the type of the file given the file's attributes.
Some questions that I'd first answer:
Is it a text file if it contains only printable characters ?
What exactly is a printable character ?
etc. etc.
Using the core API to do the rest is relatively trivial.