Official support for J2ME-based platforms, most notably Nokia S40 , ended on December 31, 2018 . At that time, users were no longer able to create new accounts or use existing ones on these devices.
public MessagingServer(int port) throws IOException serverSocket = new ServerSocket(port); clients = new HashMap<>(); Whatsapp java j2me
Nokia Symbian S60 after June 30, 2017. BlackBerry OS and BlackBerry 10 after December 31, 2017. Nokia S40 after December 31, 2018. WhatsApp.com Official support for J2ME-based platforms
Java J2ME is officially a dead platform for WhatsApp. Even lightweight messaging apps like Telegram and Signal have never supported Java. most notably Nokia S40
Clients often require a self-hosted or cloud-based server (using Docker images) to act as a bridge to modern WhatsApp APIs.