Let’s write a simple echo bot that replies with the same message
public class EchoBot {
public static void main(String[] args) {
// Create our bot instance
final Wire bot = new Wire("token");
// Configure behavior
bot.on(UpdateType.MESSAGE, ctx -> {
ctx.reply(ctx.getMessage().getText());
return null; // Mandatory!
});
// Start polling
bot.start();
}
}
As you can see the bot configuration is pretty straight forward, and if you have already used [TelegrafJS]() you’ll recognize most of the syntax.
Let’s break it down a bit.
First we create our bot instance by passing our Telegram token:
final Wire bot = new Wire("token");
Then we register a callback for incoming message updates. This is basically everything that is not a callback query:
bot.on(UpdateType.MESSAGE, ctx -> {
ctx.reply(ctx.getMessage().getText());
return null;
});
CAVEAT: Wire is written in [Kotlin](), and callbacks are implemented as functions of type (ctx: Context) -> Unit. This means that while in Kotlin we can write our lambda as:
bot.on(UpdateType.MESSAGE) { ctx ->
ctx.reply(ctx.getMessage().getText());
}
in Java we need to add return null; at the end to compensate for the Unit return type. This is unfortunate but necessary.