How can I smoothly change bucket password?

My couchbase cluster currently has no bucket password. Below is the code snippet to initialize the CouchbaseClient:

	List<String> uris = config.getUris();
	List<URI> list = new ArrayList<URI>();
	for (String s : uris) {
		try {
			URI uri = URI.create(String.format("http://%s/pools", s));
		} catch (Exception e) {
			log.error("Error happens while parse couchbase uri", e);
	try {
		client = new CouchbaseClient(list, config.getBucket(), "");
	} catch (IOException e) {
		log.error("Error happens while init couchbase client", e);

I want to set the bucket password, but not stop the online applications. So can anyone throw a light to smoothly change the password without stoping the online business?