AntiCheat

public void onHit(EntityDamageByEntityEvent e) {

    if (!(e.getDamager() instanceof Player))
        return;
    if (!(e.getEntity() instanceof Player))
        return;
    if (e.isCancelled())
        return;
    if (((LivingEntity) e.getEntity()).getNoDamageTicks() > ((LivingEntity) e
        .getDamager()).getMaximumNoDamageTicks() / 2D)
        return;

    Player p = (Player) e.getDamager();
    Player t = (Player) e.getEntity();

    if (p.hasMetadata("NPC"))
        return;
    if (t.hasMetadata("NPC"))
        return;

    if (t.isOnGround()) {

        Location l = new Location(p.getWorld(), p.getLocation().getX(), 0,
            p.getLocation().getZ());
        Location o = new Location(t.getWorld(), t.getLocation().getX(), 0,
            t.getLocation().getZ());

        CheatData pd = main.getPlayerData(p);

        pd.groundHit(l.distanceSquared(o));

    } else {

        Location l = new Location(p.getWorld(), p.getLocation().getX(), 0,
            p.getLocation().getZ());
        Location o = new Location(t.getWorld(), t.getLocation().getX(), 0,
            t.getLocation().getZ());

        CheatData pd = main.getPlayerData(p);

        pd.doubleHit(l.distanceSquared(o));

    }

    }