Java I/O How to - Display directory tree

Question

We would like to know how to display directory tree.

Answer

    /*from  w ww. ja  v  a2  s  .c om*/


import java.io.File;

class DirectoryTree {

  public static void main(String args[]) {
    File file = new File(args[0]);
    if (!file.exists()) {
      System.out.println(args[0] + " does not exist.");
      return;
    }
    tree(args[0]);
  }

  public static void tree(String filename) {
    File file = new File(filename);

    if (!file.isDirectory()) {
      System.out.println(filename);
      return;
    }

    String files[] = file.list();
    for (int i = 0; i < files.length; i++) {
      tree(filename + File.separator + files[i]);
    }
  }
}