View files in a folder

Question

I wish to make a program that has the ability to view all text files within a folder.
How easy/possible is this? I cant find any code on the internet and was wondering if any of you knew how?
also I set the background colour of my frame to black (jf.setBackground(Color.black);) and it flickers black and returns to the default colour.
why is this happening? I dont change the code after I change the colour.
thanks in advance,

Answer 1

This is what ive got now, but it doesnt work, dunno if im importing the right import.
   import java.io.FilenameFilter.*;
    public class FileChecker
      String fileNames[] = new String [10];
       FileChecker()
         System.out.println(listFiles(".txt"));
         System.out.println(fileNames());
       public String fileNames()
         fileNames[1] = listFiles(".txt");
         return fileNames[1];
       public static void main (String [] args)
         new FileChecker();
   }