public static void main(String[] args)
{
try {
// Obtain a file channel
File file = new File("filename");
FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
// Create a shared lock on the file.
// This method blocks until it can retrieve the lock.
FileLock lock = channel.lock(0, Long.MAX_VALUE, true);
// Try acquiring a shared lock without blocking. This method returns
// null or throws an exception if the file is already exclusively locked.
try {
lock = channel.tryLock(0, Long.MAX_VALUE, true);
} catch (OverlappingFileLockException e) {
// File is already locked in this thread or virtual machine
}
// Determine the type of the lock
boolean isShared = lock.isShared();
// Release the lock
lock.release();
// Close the file
channel.close();
} catch (Exception e) {
}
}