How to monitor a file?

Question

I want my program to monitor a file or directory. whenever the file or the directory is modificated, it will send an event to my program.
I use a thread to check the last modification time ever 5 seconds, but i don't think this is a good design.

Answer 1

This should help ....
class FileChangeEventManager extends Thread
     List<FileChangeEventListener> lst = new ArrayList<FileChangeEventListener>();
     List<String> lstFiles = new ArrayList<String>();
     public void fileToMonitor(String file)
          lstFiles.add(file);
     public void addListener()
          // add to list
     public void removeListener()
          // add to list
     public void run()
          while(true)
               try
                    Thread.sleep(2000);
               catch(InterruptedException e)
               // if filechanged
                     * 1. create file change event object
                     * 2. set filename
                     * 3. loop through all the listener
                     * 4. inovke filechanged(filechangeevent obj) on all listeners
class FileChangeEvent
     String fileName;
     public FileChangeEvent()
     public String getFileName() {
          return fileName;
     public void setFileName(String fileName) {
          this.fileName = fileName;
class FileChangeEventListener
     public void fileChanged(FileChangeEvent e)
}you event listeners should extends FileChangeEventListener to handle events..
enjoy !