import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.plugin.java.JavaPlugin;
import pl.kacperduras.protocoltab.ProtocolTabAPI;
import pl.kacperduras.protocoltab.manager.ProtocolTab;

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

public final class ProtocolTabExample extends JavaPlugin {

    private final ThreadLocal<SimpleDateFormat> dateFormat = ThreadLocal.withInitial(
            () -> new SimpleDateFormat("HH:mm:ss"));

    @Override
    public void onEnable() {
        this.getServer().getPluginManager().registerEvents(new Listener() {

            @EventHandler(ignoreCancelled = true, priority = EventPriority.HIGHEST)
            public void onJoin(PlayerJoinEvent event) {
                Player player = event.getPlayer();

                for (int i = 0; i < 80; i++) {
                    ProtocolTabAPI.getTablist(player).setSlot(i, ProtocolTab.BLANK_TEXT);
                }

                ProtocolTabAPI.getTablist(player).setHeader("&cmd_5 is love!");
                ProtocolTabAPI.getTablist(player).setHeader("&6md_5 is life!");

                ProtocolTabAPI.getTablist(player).setSlot(0, "First slot.");
                ProtocolTabAPI.getTablist(player).setSlot(1, "&eSecond slot.");

                ProtocolTabAPI.getTablist(player).update();
                runTask(player);
            }

        }, this);
    }

    private void runTask(Player player) {
        this.getServer().getScheduler().runTaskTimerAsynchronously(this, () -> {
          if (player == null || player.isOnline()) {
            // do something
            return;
          }
          
          ProtocolTabAPI.getTablist(player).setSlot(3, "&a" + dateFormat.get().format(
              new Date(System.currentTimeMillis())));
          ProtocolTabAPI.getTablist(player).update();
        }, 20L, 20L);
    }

}