Watching a Directory for Changes in Java

Question

I want to watch a directory for file changes. And I used WatchService in java.nio. I can successfully listen for file created event. But I can\'t listen for file modify even

Answer 1

Warning! Shameless self promotion!

I have created a wrapper around Java 1.7's WatchService that allows registering a directory and any number of glob patterns. This class will take care of the filtering and only emit events you are interested in.

DirectoryWatchService watchService = new SimpleDirectoryWatchService(); // May throw
watchService.register( // May throw
        new DirectoryWatchService.OnFileChangeListener() {
            @Override
            public void onFileCreate(String filePath) {
                // File created
            }

            @Override
            public void onFileModify(String filePath) {
                // File modified
            }

            @Override
            public void onFileDelete(String filePath) {
                // File deleted
            }
        },
        , // Directory to watch
        , // E.g. "*.log"
        , // E.g. "input-?.txt"
        ... // As many patterns as you like
);

watchService.start();

Complete code is in this repo.