How do I get a list of directories and sub-directories?

Question

Hi All,
I'm new to Java and have a couple of questions that are really stumping me and I sure could use some help.
Question 1:
I have this class file that I want to return back me a list of directories and only directories, not files. I can't figure out how to do this. I know I need to use the isDirectory() function but I can't figure out how to use it. The class file currently is returning back both directories and files. Please help!
Question 2:
Once I get the list of directories, I need to also get a listing of all subdirectories to form a directory tree starting at my File dir value (example: C:\Windows) in the constructor. Any ideas?
Thanks
import java.io.*;
public class DirList {
     private String list = "";
     public DirList(File dir){
          File f = new File(dir.toString());
          String[] files = f.list();
          for ( int i=0;i<files.length; i++ ){
               list += files[i] + "\n";
          }  // end for
     }  // end constructor
     public String getList(){
          return list;     
     }  // end method getList
}  // end class DirList

Answer 1

I'm not familiar of the recursion technique that you speek of. If
this would work, please share it with me.Okay, i'll try, I assume that you don't care what level a subfolder is right! With a selected folder (from fileChooser), you want to obtain a list of all subfolders.
After you have select a folder from the filechooser
import java.io.File;
import java.util.ArrayList;
public class AllSubFolders
  private static ArrayList allSubFolders = new ArrayList();
  public static void main(String [] args) {
    File selectedFolder = ....; //a folder seleted from the filechooser
    getSubFolder(selectedFolder );
  public static void getSubFolder(File aFolder) {
    File[] file = aFolder.listFiles();
    for (int n = 0; n < file.length; n++) {
      if (file[n].isDirectory()){
     allSubFolders.add(file[n]);
     System.out.println(file[n].getAbsolutePath());
     getSubFolder(file[n]); //recursion method call
}You can see that getSubFolder() method call it self, it will do right down to the end of the tree, try it out by replacing the line
File selectedFolder = ....; to
File selectedFolder = new File("c:\\yourFolder\\");