java vs javascript

// java
public class Bot extends ListenerAdapter {
    private JDA bot;
    public void start() {
        JDA jda = new JDABuilder("token").build();
        jda.addEventListener(this);
        bot = jda;
    }
    @Override
    public void onReady(ReadyEvent event) {
        System.out.println("logged in on" + bot.getBot().getSelfUser().getAsTag() + "");
    }
    @Override
    public void onMessageReceived(@Nonnull MessageReceivedEvent event) {
        if (event.getMessage().getContentRaw().contains("ping")) {
            event.getChannel().sendMessage("@" + event.getAuthor().getAsTag() + ", Pong!").queue();
        }
    }
}
public class Main {
    public static void main(String[] args) {
        Bot bot = new Bot();
        bot.start();
    }
}
// JavaScript
const Discord = require('discord.js');
const client = new Discord.Client();
client.on('ready', () => {
    console.log(`Logged in as ${client.user.tag}!`);
});
client.on('message', msg => {
    if (msg.content.includes('ping')) {
        msg.reply('Pong!');
    }
});
client.login('token');