The UI was built using javax.microedition.lcdui :
This is where the history of WhatsApp J2ME takes a controversial turn. Whatsapp java j2me
If your contacts use WhatsApp, you can’t directly message them via SMS. However, services like or Twilio allow your Java phone to send SMS messages that forward to WhatsApp using API bridges. Again, this is not plug-and-play. The UI was built using javax
While the original J2ME app is long gone, Java is far from dead in the WhatsApp ecosystem. Today, Java is widely used on the to interact with WhatsApp’s APIs. Whatsapp java j2me