Scoreboard easy

package io.github.RyuGamer97;

import org.bukkit.ChatColor;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityDamageEvent;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.scoreboard.DisplaySlot;
import org.bukkit.scoreboard.Objective;
import org.bukkit.scoreboard.Scoreboard;
import org.bukkit.scoreboard.ScoreboardManager;

public class healthBar extends JavaPlugin
{

	@Override
	public void onEnable()
	{
		getServer().getPluginManager().registerEvents(new Listener(){
			@EventHandler
			public void entityDamage(EntityDamageEvent e){
				if(e.getEntity() instanceof Player){
					Player p = (Player) e.getEntity();
					ScoreboardManager sbm = getServer().getScoreboardManager();
					Scoreboard sb = sbm.getNewScoreboard();
					Objective obj = sb.registerNewObjective("showhealth", "health");
					obj.setDisplaySlot(DisplaySlot.BELOW_NAME);
					obj.setDisplayName(ChatColor.RED + "HP");
					for (Player online : getServer().getOnlinePlayers()){
					online.setScoreboard(sb);
					}
				}
			}
		}, this);
	}

}