websocket string onMessage, gives java.lang.IllegalStateException: Binary message handler not found

I have a websocket setup using javax.websocket, it seems to connect, but wont work, it keeps giving a java.lang.IllegalStateException: Binary message handler not found

            final WebSocketContainer webSocketContainer = ContainerProvider.getWebSocketContainer();
            Session session = webSocketContainer.connectToServer(new Endpoint() {
                 @Override
                public void onError(Session session, Throwable thr) {
                    // TODO Auto-generated method stub
                    super.onError(session, thr);
                    System.out.println("checkerWindow.DownloadMessages().new Endpoint() {...}.onError()");
                    thr.printStackTrace();
                }

                @Override
                 public void onOpen(Session session, EndpointConfig EndpointConfig) {
                    System.out.println("checkerWindow.DownloadMessages().new Endpoint() {...}.onOpen()");

                     try {
                         //send login details
                         //login:<deviceid>:<secret>\n
                         session.getBasicRemote().sendText("login:"+deviceid+":"+secret+"\n");
                     }
                    catch(Exception ex){
                        System.err.println("Exception=" + ex.toString());
                        ex.printStackTrace();
                    }
                 }

                 @OnMessage
                 public void onMessage(String message) {
                     System.out.println("Received message: "+message);
                 }

                 @Override
                 public void onClose(Session session, CloseReason closeReason) {
                     System.out.println("checkerWindow.DownloadMessages().new Endpoint() {...}.onClose()");
                 }

             }, ClientEndpointConfig.Builder.create().build(), URI.create("wss://client.pushover.net/push"));

I have tried the ByteBuffer but the compiler doesnt like that.

You should define a method to receive binary messages. For example,

@OnMessage
public void onMessage(byte[] message) {
    ......
}

See the JavaDoc of OnMessage annotation for details.