telegram_example/src/main/java/org/telegram/commands/HelloCommand.java

package org.telegram.commands;

import lombok.extern.slf4j.Slf4j;
import org.telegram.database.DatabaseManager;
import org.telegram.telegrambots.extensions.bots.commandbot.commands.BotCommand;
import org.telegram.telegrambots.meta.api.methods.send.SendMessage;
import org.telegram.telegrambots.meta.api.objects.Chat;
import org.telegram.telegrambots.meta.api.objects.User;
import org.telegram.telegrambots.meta.exceptions.TelegramApiException;
import org.telegram.telegrambots.meta.generics.TelegramClient;

/**
 * This command simply replies with a hello to the users command and
 * sends them the 'kind' words back, which they send via command parameters
 *
 * @author Timo Schulz (Mit0x2)
 */
@Slf4j
public class HelloCommand extends BotCommand {

    private static final String LOGTAG = "HELLOCOMMAND";

    public HelloCommand() {
        super("hello", "Say hallo to this bot");
    }

    @Override
    public void execute(TelegramClient telegramClient, User user, Chat chat, String[] arguments) {

        if (!DatabaseManager.getInstance().getUserStateForCommandsBot(user.getId())) {
            return;
        }

        String userName = chat.getUserName();
        if (userName == null || userName.isEmpty()) {
            userName = user.getFirstName() + " " + user.getLastName();
        }

        StringBuilder messageTextBuilder = new StringBuilder("Hello ").append(userName);
        if (arguments != null && arguments.length > 0) {
            messageTextBuilder.append("\n");
            messageTextBuilder.append("Thank you so much for your kind words:\n");
            messageTextBuilder.append(String.join(" ", arguments));
        }

        SendMessage answer = new SendMessage(chat.getId().toString(), messageTextBuilder.toString());

        try {
            telegramClient.execute(answer);
        } catch (TelegramApiException e) {
            log.error("Error", e);
        }
    }
}