Not more than 4 files in a directory .... ?????

Question

Hi
Do you know how can restrict a directory only to allow 4 files ....
I have a program in C who save image every second, and if i leave it running mayby i have to said good bye HD space, :)
Thge point is that i want to use the output, but i only want 4 files .... not a sequence .... i mean
cam1.bmp , cam2.bmp, .... cam9.bmp ..... cam23.bmp ...
i neen cam1.bmp, cam2.bmp, cam3.bmp, cam4.bmp ....and cam5 is now CAM1.bmp and cam6 is cam2.bmp ...i mean delete the old one and use the new image but with the same name ......
please ...help me .... i only need to know how or what can i use to start developing ....
Thank you !!!
:)

Answer 1

This fixes a couple of the problems with the previous ones renameTo needs a file and I forgot some semi colons.
import java.io.*;
import java.util.*;
public class CleanUp
     public static void main(String args[])
          throws IOException
          // Check arguments 
          if(args.length==0)   
               System.out.println("Usage: java <directory with the images>"); 
          // Delete other files 
          FileFilter filter=new FileFilter() 
               public boolean accept(File path)   
                    return (!path.getName().endsWith(".bmp"));   
          File dir=new File(args[0]); 
          File[] files=dir.listFiles(filter); 
          for(int i=0; i<files.length; i++)   
          files.delete();
          // Get list of files
          filter=new FileFilter()
               public boolean accept(File path)
                    return (path.getName().endsWith(".bmp"));
          files=dir.listFiles(filter);
          Arrays.sort(files);
          // Check length
          if(files.length<4)
               return;
          // Delete the older files
          for(int i=0; i<files.length-4; i++)
               files[i].delete();
          // Rename newest files
          for(int i=files.length-4; i<files.length; i++)
               files[i].renameTo(new File("cam"+i+".bmp"));