Process incoming files in a directory

Question

I want to make a Java program that monitors a directory continuously for a new file,

and if a new file arrives, process it and then delete it.

What is the best way to do this?

Answer 1

Check for new files, process them, rinse, and repeat:

while (true) {
    File[] files = new File(DIRECTORY_PATH).listFiles();
    for (File file : files) {
        /* do something with this file */

        //and delete it when finished
        file.delete();
    }

    //Pause for a second before checking again
    Thread.sleep(1000);
}

Answer 2

JDK 7 includes the java.nio.file.WatchService class that allows you to be notified of filesystem changes when they happen rather than continuously poll. It is currently available in OpenJDK as well:

JDK 7 features

OpenJDK WatchService tutorial