Change prefix for Discord bot in Java

How do I change my Discord bot's prefix in Java? Here is my code:

package Rekt.YourAssistant;
 
import javax.security.auth.login.LoginException;

import net.dv8tion.jda.api.JDA;
import net.dv8tion.jda.api.JDABuilder;

public class Main {
	public static JDA jda;
	
	//Main Method
	public static void main(String[] args) throws LoginException {
		jda = JDABuilder.createDefault("NzU4MTIxMTkwMjExNDUyOTQ4.X2qVYA.aW6C3UrekBZQrmA-AmMxYEMyibI").build();
	}
}

I do not know anything about the JDA but it appears not to have a command handler out of the box - you'd need to find and install one or write your own.
Therefore, prefixes are not a pre-managed concept. Here's is how the JDA Github example shows making one command (simplified by me to get to the relevant information):

public class MessageListenerExample extends ListenerAdapter
{
    public static void main(String[] args)
    {
       //start bot
    }

    @Override
    public void onMessageReceived(MessageReceivedEvent event)
    {
        //These are provided with every event in JDA
        JDA jda = event.getJDA();

        Message message = event.getMessage();           //The message that was received.

        String msg = message.getContentDisplay();              //This returns a human readable version of the Message. Similar to
                                                        // what you would see in the client.

        if (event.isFromType(ChannelType.TEXT))         //If this message was sent to a Guild TextChannel
        {
           if (msg.equals("!ping"))
           {
             //do something
           }
           if (msg.startsWith("!alias"))
           {
             //do something else
           }
        }
     }
}

Notice that the if msg.equals or msg.startsWith methods act on strings with their own prefix: !

I highly recommend you read the entire example as there is a LOT I cut out to just show the prefix part.

P.S. You should regenerate the Bot Token you posted in your question. It's on the internet now, and with it people can take control of you bot. When you post another question you can just write "my-token-goes-here" and people will know what you mean.

You can use a GuildMessageReceivedEvent and then use

// Set This Prefix String To Whatever You want As Your Prefix
String prefix = "/"
if(event.getMessage().getContentRaw.equals(prefix + "help"){
   event.getMessage().getChannel().sendMessage("You used /help command");
}