by: Keith Fenske, https://kwfenske.github.io/
CompareFolders is a Java 1.4 application to compare two folders to determine if all files and subfolders are identical. The folders may be on the same computer, on the local network, or they may be represented by checksum files. Files or subfolders that are not the same are reported to the user. The intention is to decide if two different distribution folders have the same contents. You can:
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Compare two folders. One or both folders may be represented by checksum files.
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Create a checksum file for a folder. This is the most efficient way of remembering the contents of a folder for later comparison. After you back up files to external media, and later restore them, how will you know they are correct unless you have checksums from the original files?
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Update a checksum by assuming that files have not changed if they have the same name, date, and size. This is much faster than creating a new checksum for large collections on a local disk drive. However, it is not recommended for files copied over a network or downloaded from the internet.
Checksum files are used when the original files or folders are not available. A checksum file is a plain text file in XML (Extensible Markup Language) format with the name, size, and checksums for each file. Checksums are small hexadecimal "signatures" for testing whether or not files have been copied correctly, such as over a network. One person sends a file along with the checksum computed on the original computer. A second person calculates a similar checksum for the received file, and if the two checksums agree, then the received file is assumed to be correct. This CompareFolders application supports CRC32, MD5, SHA1, and optional SHA256 or SHA512 checksums. It is extremely unlikely that two files will have the same MD5 or the same SHA checksum and still be different (which can't be said about CRC32).
Download the ZIP file here: https://kwfenske.github.io/compare-folders-java.zip
Released under the terms and conditions of the Apache License (version 2.0 or later) and/or the GNU General Public License (GPL, version 2 or later).
