Watch Service API

Abstract

The Watch Service API was introduced in Java 7 (NIO.2) as a thread-safe service that is capable of watching objects for changes and events. The most common use is to monitor a directory for changes to its content through actions such as create, delete, and modify. You’ve probably seen the effect of such a service many times. For example, when you open a text file in an editor (such as GridinSoft Notepad, jEdit, etc.) and the file content is modified outside the editor, you will see a message that asks whether you want to reload the file because it was modified. This means the editor has detected a file change through a watch service and is reporting it accordingly. This is known as the file change notification mechanism, and starting with NIO.2, it is available through the Watch Service API.