Like this we can watch any objects for changes. So to watch this file for changes we can use WatchService and Watchable. Now the other editor will alert with a message saying “The file is edited, do you want to load the latest version?” At the same time, we have opened that same file using another editor and edited it. Imagine we have a file editor and it has a file loaded. WatchService and Watchable provides the framework to watch registered object for changes using Java. It has got a set of interfaces and classes to help this job done. NIO package was a significant update in this version. So we have got the above real time scenarios and how do we solve it using Java? Java version 7 provided an update for IO package. We may have a FTP folder where in an external system will post a file and our program has to monitor that FTP folder and when a new file arrives we need to read it or email it. Lets think of an use, a java program should monitor a folder and it should alert if a new file is created.

Watch folder program