Getting Started

Getting started

Sdcf4j uses annotations to indicate commands. Let's start creating a simple info command which gives some information about the bot.

Creating a class for the command

You can create commands in every class which implementes the CommandExecutor interface. The interface has no methods, but is used to mark the class as command executor.

Your class may look like this:

package <your.package>;

import de.btobastian.sdcf4j.CommandExecutor;

public class InfoCommand implements CommandExecutor {

}

Now you have to create a method which will be invoked when someone uses the command. The name, parameters and return-type of the method are dynamic so you have to to decide what you need. Our info command only needs String as return-type and maybe the arguments of the command if you want to support stuff like !info author. In our example we want to support the following commands:

• !info Gives a rough overview about the bot.
• !info author Gives some information about the author of the bot like name and age.
• !info time Shows the current time (don't ask me why we need such a command).

package <your.package>;

import de.btobastian.sdcf4j.Command;
import de.btobastian.sdcf4j.CommandExecutor;

public class InfoCommand implements CommandExecutor {

    @Command(aliases = {"!info", "!i" }, description = "Shows some information about the bot.", usage = "!info [author|time]")
    public String onInfoCommand(String[] args) {
        return null; // dummy return type
    }

}

The aliases array contains all commands you can use. In our example it's !info and as a shortcut !i. The description and usage is required for help commands. I will come to this later. The args-parameter is a String array which contains all arguments of the command. For !info abc def 123 the array would be ["abc", "def", "123"]. The returned String is what the bot will "say". You can use void, int, etc., too if you don't want an output, a number as output, ...

The implementation is pretty easy now:

package <your.package>;

import de.btobastian.sdcf4j.Command;
import de.btobastian.sdcf4j.CommandExecutor;

import java.text.SimpleDateFormat;
import java.util.Date;

public class InfoCommand implements CommandExecutor {

    @Command(aliases = "!info", description = "Shows some information about the bot.", usage = "!info [author|time]")
    public String onInfoCommand(String[] args) {
        if (args.length > 1) { // more than 1 argument
            return "Too many arguments!";
        }
        if (args.length == 0) { // !info
            return "- **Author:** <YourName>\n" +
                   "- **Language:** Java\n" +
                   "- **Command-Lib:** sdcf4j";
        }
        if (args.length == 1) { // 1 argument
            if (args[0].equals("author")) { // !info author
                return "- **Name:** <YourName>\n" +
                       "- **Age:** <YourAge>\n" +
                       "- **Website:** <YourWebsite>";
            }
            if (args[0].equals("time")) { // !info time
                SimpleDateFormat format = new SimpleDateFormat("HH:mm");
                Date currentDate = new Date(System.currentTimeMillis());
                return "It's" + format.format(currentDate);
            }
        }
        return "Unknown argument!";
    }

}

Registering the command executor

Depending on your library the registration looks a little bit different. I assume you know how to login with your used library so I won't explain this.

Javacord

DiscordApi api; // Your api instance. Of course it should be initialized!
CommandHandler handler = new JavacordHandler(api);
handler.registerCommand(new InfoCommand());

JDA3

JDA jda; // Your JDA instance. Of course it should be initialized!
CommandHandler handler = new JDA3Handler(jda);
handler.registerCommand(new InfoCommand());

Discord4J

IClient client; // Your client instance. Of course it should be initialized!
CommandHandler handler = new Discord4JHandler(client);
handler.registerCommand(new InfoCommand());

Note: If your executor contains more than one command you do not have to register it more than one time.