Read directory structure into tree structure

Question

Hi ya,
I want to be able to write a command line program that either takes a root node(directory root) or just takes the directory root from where the program is run reads in the directory tree into a tree structure. Then I want to analyse the tree.
I would like to know what are the best ways to do this and what are the most useful classes.
Thanks a lot for the help,
Martin

Answer 1

Here is a quickie du(1) (disk usage) clone that should give some hints. The Getopt class is something I wrote so you won't be able to compile this as such.
import java.io.File;
public class Du
    public static void main(String args[])
        boolean sum_mode = false;
        Getopt getopt = new Getopt(args, "sk");
        while (getopt.next()) {
            switch (getopt.option()) {
              case 's':
                  sum_mode = true;
                  break;
              case 'k':
                  break;
              default:
                  System.err.println("du: unknown option \"-" + getopt.optionName() + "\"");
                  System.exit(1);
        if (getopt.parameterCount() == 0) {
            du(new File("."), ".", sum_mode, true);
        } else {
            for (int n = 0; n < getopt.parameterCount(); n++) {
                String name = getopt.parameter(n);
                du(new File(name), name, sum_mode, true);
    private static long du(File file, String path, boolean sum_mode, boolean topmost_file)
        long bytes = 0;
        if (file.isDirectory()) {
            File files[] = file.listFiles();
            String sub_path = path + "/" + file.getName();
            for (File f : files)
                bytes += du(f, sub_path, sum_mode, false);
            if (!sum_mode || topmost_file)
                System.out.println((bytes / 1024) + "\t" + path + "/" + file.getName());
        } else {
            bytes = file.length();
            if (topmost_file)
                System.out.println((bytes / 1024) + "\t" + path + "/" + file.getName());
        return bytes;
}