Solved Unknown error..

Care to explain what's the error or output on that?

 

• check to see if event is actually firing (debug messages)
• once knowing event fires, make sure player has the permission specified

 

If you try to use /, java will read it as a special character. instead use // so it will ignore it

*EDIT* sorry thats for \, ignore this

 

he is using forward slash, not back

 

yeah, I edited my message. thanks for pointing it out tho!

 

check if it's firing.

Code (Java):

@EventHandler
public void onPlayerJoin(PlayerJoinEvent event) {
     System.out.println("event fired");
}

 

no, your command and message output is fine. check if your event is firing.

 

Well to add color to messages you need to either use the ChatColor enum or transalte the whole message to color using ChatColor.translateAlternateColor() (not sure about the exact name, but it takes a char as first parameter it beign the color code denominator & and then as second argument the String to translate)

 

Did you register the event in your plugin onEnable()?

 

register the event. ex:

Code (Java):

public class Main extends JavaPlugin {
     
      @Override
      public void onEnable() {
           getServer().getPluginManager().registerEvents(new ListenerClass(), this);
      }
}

public class ListenerClass implements Listener {

      @EventHandler
      public void onPlayerJoin(PlayerJoinEvent event) {
            Bukkit.getOnlinePlayers().stream().filter(Player::isOp).forEach(p -> p.sendMessage("you received a message since you were op!");
      }
}