List all files under directory recursively, like UNIX ls or DOS and VMS dir

 
import java.io.File;

public class Main {
  public static void main(String[] argv) {
    doDir(".");
  }

  private static void doDir(String s) {
    File f = new File(s);
    if (!f.exists()) {
      System.out.println(s + " does not exist");
      return;
    }
    if (f.isFile()) {
      doFile(f);
    } else if (f.isDirectory()) {
      System.out.println("d " + f.getPath());
      String objects[] = f.list();

      for (int i = 0; i < objects.length; i++) {
        doDir(s + f.separator + objects[i]);
      }
    } else {
      System.err.println("Unknown: " + s);
    }
  }

  private static void doFile(File f) {
    System.out.println("f " + f.getPath());
  }
}