Question

So I am writing a code that locates certain information on Protein databases. I know that a recursive folder search is the best possible way to locate these files, but I am very new to this language and have been told to write in Java (I normally do C++)

SO this being said, what method would i use to:

First: Locate the folder on desktop
Second: Open each folder and that folders subfolders
Third: Locate files that end with the “.dat” type (because these are the only files that have stored the Protein information

Thanks for any and all help you can provide

Answer 1

1. java.io.File is “An abstract representation of file and directory pathnames”
2. File.listFiles provides a listing of all the files contained within the directory (if the File object represents a directory)
3. File.listFiles(FileFilter) provides you with the ability to filter a file list based on your needs

So, with that information…

You would specify a path location with something like…

File parent = new File("C:/path/to/where/you/want");

You can check that the File is a directory with…

if (parent.isDirectory()) {
    // Take action of the directory
}

You can list the contents of the directory by…

File[] children = parent.listFiles();
// This will return null if the path does not exist it is not a directory...

You can filter the list in a similar way…

File[] children = parent.listFiles(new FileFilter() {
        public boolean accept(File file) {
            return file.isDirectory() || file.getName().toLowerCase().endsWith(".dat");
        }
    });
// This will return all the files that are directories or whose file name ends
// with ".dat" (*.dat)

Other useful methods would include (but not limited to)

• File.exists to test that the file actually exists
• File.isFile, basically instead of saying !File.isDirectory()
• File.getName(), returns the name of the file, excluding it’s path
• File.getPath() returns the path and name of the file. This can be relative, so be careful, see File.getAbsolutePath and File.getCanonicalPath to resolve this.
• File.getParentFile which gives you access to the parent folder