Add basic ping response

src/main/java/wtf/beatrice/hidekobot/HidekoBot.java

@@ -3,6 +3,8 @@ package wtf.beatrice.hidekobot;
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.JDABuilder;
 import net.dv8tion.jda.api.entities.Activity;
+import net.dv8tion.jda.api.requests.GatewayIntent;
+import wtf.beatrice.hidekobot.listeners.MessageListener;
 import wtf.beatrice.hidekobot.utils.Logger;
 
 import javax.security.auth.login.LoginException;
@@ -38,8 +40,13 @@ public class HidekoBot
             // try to create the bot object and authenticate it with discord.
             jdaBuilder = JDABuilder.createDefault(botToken);
             jdaBuilder.setActivity(Activity.playing("the piano"));
-            jda = jdaBuilder.build();
-        } catch (LoginException e)
+
+            jdaBuilder.enableIntents(GatewayIntent.MESSAGE_CONTENT,
+                    GatewayIntent.DIRECT_MESSAGES,
+                    GatewayIntent.GUILD_MESSAGES);
+
+            jda = jdaBuilder.build().awaitReady();
+        } catch (LoginException | InterruptedException e)
         {
             logger.log(e.getMessage()); // print the error message, omit the stack trace.
             return; // if we failed connecting and authenticating, then quit.
@@ -55,6 +62,10 @@ public class HidekoBot
         // log the invite-link to console so noob users can just click on it.
         logger.log("Bot User ID: " + botUserId, 4);
         logger.log("Invite Link: " + standardInviteLink, 5);
+
+        // register listeners
+        jda.addEventListener(new MessageListener());
+
     }
 
 }

src/main/java/wtf/beatrice/hidekobot/listeners/MessageListener.java

@@ -0,0 +1,24 @@
+package wtf.beatrice.hidekobot.listeners;
+
+import net.dv8tion.jda.api.entities.*;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import net.dv8tion.jda.api.hooks.ListenerAdapter;
+import org.jetbrains.annotations.NotNull;
+import wtf.beatrice.hidekobot.utils.Logger;
+
+public class MessageListener extends ListenerAdapter
+{
+
+    private final Logger logger = new Logger(MessageListener.class);
+
+    @Override
+    public void onMessageReceived(@NotNull MessageReceivedEvent event)
+    {
+        if(event.getMessage().getContentDisplay().equalsIgnoreCase("ping"))
+        {
+            MessageChannel channel = event.getChannel();
+            channel.sendMessage("Pong!").queue();
+        }
+    }
+
+}