Frequently Asked Questions

# Check your Java version
java -version

fun main() {
    val jda = light(BOT_TOKEN)
    
    jda.onCommand("ping") { event ->
        val time = measureTime {
            event.reply("Pong!").await()
        }.inWholeMilliseconds
        
        event.hook.editOriginal("Pong: $time ms").queue()
    }
}

https://discord.com/api/oauth2/authorize?client_id=YOUR_CLIENT_ID&permissions=0&scope=bot%20applications.commands

JDABuilder.createDefault(token,
    GatewayIntent.GUILD_MESSAGES,
    GatewayIntent.MESSAGE_CONTENT
).build();

// For slash command bots (no message commands)
JDA jda = JDABuilder.createLight(token, Collections.emptyList())
    .build();

// For general bots
JDA jda = JDABuilder.createDefault(token, 
    GatewayIntent.GUILD_MESSAGES,
    GatewayIntent.MESSAGE_CONTENT
).build();

jda.updateCommands().addCommands(
    Commands.slash("ping", "Check bot latency"),
    Commands.slash("echo", "Repeat a message")
        .addOption(OptionType.STRING, "message", "The message to repeat", true)
).queue();

@Override
public void onSlashCommandInteraction(SlashCommandInteractionEvent event) {
    if (event.getName().equals("ping")) {
        long time = System.currentTimeMillis();
        event.reply("Pong!").setEphemeral(true)
            .flatMap(v -> event.getHook()
                .editOriginalFormat("Pong: %d ms", 
                    System.currentTimeMillis() - time)
            ).queue();
    } else if (event.getName().equals("echo")) {
        String message = event.getOption("message").getAsString();
        event.reply(message).queue();
    }
}

// Guild commands update instantly
guild.updateCommands().addCommands(
    Commands.slash("test", "Testing command")
).queue();

event.reply("Choose an option:")
    .addActionRow(
        Button.primary("button1", "Option 1"),
        Button.secondary("button2", "Option 2"),
        Button.danger("cancel", "Cancel")
    )
    .queue();

@Override
public void onButtonInteraction(ButtonInteractionEvent event) {
    switch (event.getComponentId()) {
        case "button1" ->
            event.reply("You chose option 1!").setEphemeral(true).queue();
        case "button2" ->
            event.reply("You chose option 2!").setEphemeral(true).queue();
        case "cancel" ->
            event.getMessage().delete().queue();
    }
}

StringSelectMenu menu = StringSelectMenu.create("menu:options")
    .addOption("Option A", "a", "Description A")
    .addOption("Option B", "b", "Description B")
    .addOption("Option C", "c", "Description C")
    .build();

event.reply("Select an option:")
    .addActionRow(menu)
    .queue();

event.reply("Done!").queue();

event.deferReply().queue();
// Do long task...
event.getHook().sendMessage("Finished!").queue();

event.deferReply(true).queue();

// This does NOTHING - no request is sent!
channel.sendMessage("Hello");

// This sends the message
channel.sendMessage("Hello").queue();

// With callback
channel.sendMessage("Hello").queue(
    message -> System.out.println("Sent: " + message.getId()),
    error -> System.err.println("Failed: " + error)
);

channel.sendMessage("Delete in 10 seconds...")
    .delay(10, TimeUnit.SECONDS)
    .flatMap(Message::delete)
    .queue();

RestAction.allOf(
    channel1.sendMessage("Message 1"),
    channel2.sendMessage("Message 2"),
    channel3.sendMessage("Message 3")
).queue();

RestAction<Member> action1 = guild.retrieveMemberById(id1);
RestAction<Member> action2 = guild.retrieveMemberById(id2);

action1.and(action2, (member1, member2) -> {
    // Both members retrieved
    return member1.getEffectiveName() + " and " + member2.getEffectiveName();
}).queue(result -> System.out.println(result));

// ✅ Good - async in event handler
@Override
public void onMessageReceived(MessageReceivedEvent event) {
    event.getChannel().sendMessage("Hello").queue();
}

// ❌ Bad - blocking in event handler
@Override
public void onMessageReceived(MessageReceivedEvent event) {
    Message msg = event.getChannel().sendMessage("Hello").complete();
}

dependencies {
    implementation("net.dv8tion:JDA:6.3.1")
    implementation("dev.arbjerg:lavaplayer:2.2.2")
}

JDABuilder.createDefault(token)
    .setAudioSendFactory(new NativeAudioSendFactory())
    .build();

// Minimal caching for slash command bots
JDABuilder.createLight(token)
    .setEnabledCacheFlags(EnumSet.noneOf(CacheFlag.class))
    .build();

// Selective caching
JDABuilder.createDefault(token)
    .setMemberCachePolicy(MemberCachePolicy.VOICE)
    .disableCache(
        CacheFlag.ACTIVITY,
        CacheFlag.CLIENT_STATUS,
        CacheFlag.EMOJI,
        CacheFlag.STICKER
    )
    .build();

JDABuilder.createLight(token)
    .setChunkingFilter(ChunkingFilter.NONE)
    .build();

DefaultShardManagerBuilder.createDefault(token)
    .setShardsTotal(4) // Or -1 for automatic
    .addEventListeners(new MyListener())
    .build();

// ❌ Bad - Makes 100 individual requests
for (int i = 0; i < 100; i++) {
    channel.sendMessage("Message " + i).queue();
}

// ✅ Better - Batch with delays
for (int i = 0; i < 100; i++) {
    int finalI = i;
    channel.sendMessage("Message " + finalI)
        .delay(i, TimeUnit.SECONDS)
        .queue();
}

# .gitignore
.env
config.properties
bot-token.txt

String token = System.getenv("BOT_TOKEN");
if (token == null) {
    throw new IllegalStateException("BOT_TOKEN not set!");
}

Properties config = new Properties();
config.load(new FileInputStream("config.properties"));
String token = config.getProperty("token");

Runtime.getRuntime().addShutdownHook(new Thread(() -> {
    jda.shutdown();
    try {
        if (!jda.awaitShutdown(Duration.ofSeconds(10))) {
            jda.shutdownNow();
            jda.awaitShutdown();
        }
    } catch (InterruptedException e) {
        jda.shutdownNow();
    }
}));