JavaTailer monitors files for appended data much like the Unix tail command.

This implementation uses the NIO.2 WatchService to monitor file events and thus version 7 or greater of Java® is required.

The "tailer" runs in its own thread and utilizes a callback mechanism that the user implements to notify of file change events.

License

This software is licensed under the Apache License, v2.0. See the LICENSE file. The Copyright notice is contained in the NOTICE file.

Using

See TailerTest.java for a working example of how to instantiate the thread and build your callback object.

Short version:

TailerThread tailer = new TailerThread(callback, "/home/me", "fileToMonitor.txt");
tailer.start(); // start the thread
if (!tailer.waitForStart(2000)) {
    throw new RuntimeException("TailerThread didn't start up within 2s");
} 

Then add lines to /home/me/fileToMonitor.txt and the receiveEvent() in your TailerCallback implementation will receive the appended lines.

To signal the thread to stop:

tailer.interrupt();

Building

The build system is gradle. To build:

gradle build

To run just the tests:

gradle test

To install the gradle wrapper (perhaps for your IDE):

gradle wrapper --gradle-version 2.12

Or, if you prefer, replace 2.12 with the latest Gradle version.

To publish to your local maven repository: gradle publishToMavenLocal