Check if file exists without knowing the file name

Question

I'm new to Java and am working on a program that needs to check a folder every couple of min to see if a file has been placed there, then open the file, read it and then change the name.
The file name will be similar to 20020905 (the current date, but I don't know if the time will be appended to the name or not), but will not have a file extention.
If anyone could point me in the right direction, I'd appreciate it.

Answer 1

why go about it using the file name? Why not use the lastModifiedDate, which will be less then the last time you checked, e.g.:
Date lastCheck = new Date();
while(true) {
  try {
     Thread.sleep(yourDelay);
  catch(Excepiton e) { }
  File [] files = yourDirectory.listFiles();
  for (int i = 0; i < files.length; i++) {
    if (files.isDirectory()) {
//skip directories
continue;
Date modified = new Date(files[i].lastModified());
if (lastCheck.before(modified)) {
System.out.println(files[i].getName() + " is new");
//update time of last check
lastCheck = new Date();
That code isn't real exact, but it gives you an idea. I think using the lastModified date is a little more elegant then keying off file name conventions, but use what ever works best. If you use code like I suggested, depending upon how often files are added you might have to account for a possiblity where a file is created while you are iterating through that 'for' loop, meaning its file creation date qualifies it for your condition, but it will be less then the newly updated lastCheck value.