File Operations in Java

Question

I'm working on a small application in Java that takes a directory structure and renames the files according to a certain format, after parsing the original name.

What is the best Java class / methodology to use in order to facilitate these file operations?

Edit: the question is only regarding the file operations part, I got the "getting the formatted name" down :)

Edit 2: Also, how do I list files recursively?

Answer 1

There's the class File, that does all you need:

• listFiles()
• renameTo()

Answer 2

Use java.io.File

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Listing all files in a directory

http://www.javaprogrammingforums.com/java-code-snippets-tutorials/3-how-list-all-files-directory.html

File folder = new File(path);
File[] listOfFiles = folder.listFiles(); 
for (int i = 0; i < listOfFiles.length; i++) {
    // Do something with "listOfFiles[i]"
}

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UPDATE

To list the files recursively, your best approach is fairly easy:

• Create a queue of directories. Initially add the first directory to the queue
• Pop the first directory element off the queue.
• List all files in that directory, same as above
• Iterate over all the files in that directory
• If a file is a directory (use isDirectory() method), add it to the back of the queue. Else, process this next file as needed (e.g. print)
• Stop when the queue is empty.

An example (I think a bit different from my approach above) is http://www.javapractices.com/topic/TopicAction.do?Id=68

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Renaming a file

http://www.roseindia.net/java/example/java/io/RenameFileOrDir.shtml

    boolean Rename = oldfile.renameTo(newfile);

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Finding a new name to rename to

I'm not sure what you want the formatting rules to be - when I implemented the same utility in Perl for my own use I used Regular Expressions. For Java, that'd be java.util.regex

Answer 3

This Sun Totorial could be a good start. If I where you I would basically retrieve all the files in the directory and then loop through them, as shown here. You might have to use regular expressions as well, a basic tutorial can be found here

Answer 4

You can always use the standard java.io.File class, but it's primitive and not very useful on its own.

For complex file-I/O operations, I recommend using Apache Commons IO, which provides a rich class library for (among other things) file operations. See classes like FileUtils and FilesystemUtils