Hello everybody, Everything works well avec 4 files, Lion.avi.part6, Lion.avi.part23, Lion.avi.part36, Lion.avi.part53. I had used a map with the number of each files (for the key) and the file name (for value). With the keys (numbers), the TreeMap gives the order of the files When I used Debug, every flow was closed. I don't understand why my program is not validate. With BufferedInputStream et BufferedOutputStream, I used buffers.