Why does this program fall into endless loop?

Hello EveryBody:
Here is a small demo:

import java.io.*;
import java.util.*;
class DeleteDir{
    public DeleteDir(File dir){
        if(dir.isDirectory()){
            LinkedList dirs = new LinkedList();
            dirs.add(dir);
            while(dirs.size() > 0){
                File currentDir = (File)dirs.getFirst();
                File[] files = currentDir.listFiles();
                boolean emptyDir = true;
                for(int i= 0; i<files.length; i++){
                    if(files[i].isFile()){
                        System.out.println("Deleting..." + files[i].getAbsolutePath());
                        try{
                            files[i].delete();
                        }catch(SecurityException se){
                            se.printStackTrace();
                                }
                    }else{
                        dirs.addFirst(files[i]);
                        emptyDir = false;
                    }
                }

                if(emptyDir){
                    System.out.println("Deleting... " + currentDir.getAbsolutePath());
                    try{
                        currentDir.delete();
                    }catch(SecurityException se){
                        se.printStackTrace();
                            }
                    dirs.removeFirst();
                    }
                }
        }else if(dir.isFile()){
            System.out.println("Error: " + dir.getName() + " is a file");
        }else System.out.println("Error: " + dir.getName() + " is unknown");

        }
    public static void main(String[] args){
        File dir = new File(args[0]);
        DeleteDir delDir = new DeleteDir(dir);
            }
    }

When I excute "java DeleteDir experiment",it goes to endless loop.
Deleting... F:\java\practise\practise8\experiment\experiment\experiment
Deleting... F:\java\practise\practise8\experiment\experiment\experiment
Deleting... F:\java\practise\practise8\experiment\experiment\experiment
Deleting... F:\java\practise\practise8\experiment\experiment\experiment
.......
Only by Ctrl+c can I stop it!

Experiment here is a directory in which there is only another directory
named experiment which includes an empty directory named experiment
again in it.Mayb you will feel puzzled.Tree this directory,we can get:
????experiment
   ????experiment
       ????experiment

That's the whole of my question!
Any help will be greatly appreciated!

Dowson.