TitleManager.java

package de.oppermann.bastian.spleef.util;

import de.oppermann.bastian.spleef.SpleefMain;
import org.bukkit.Bukkit;
import org.bukkit.entity.Player;

import java.lang.reflect.Constructor;
import java.util.logging.Level;

/*
 * Code by https://www.spigotmc.org/threads/send-titles-to-players-using-spigot-1-8-1-10-2.48819/
 * (with some small modifications)
 */
public class TitleManager {

    private static boolean nmsFailed = false;

    /**
     * Sends a title to player
     *
     * @param player      Player to send the title to.
     * @param text        The text displayed in the title.
     * @param subtitle    Whether the title should be a subtitle or a normal title.
     * @return Whether the sending failed or succeed.
     */
    public static boolean sendTitle(Player player, String text, boolean subtitle) {
        if (nmsFailed) {
            return false;
        }
        try {
            Object chatTitle = getNMSClass("IChatBaseComponent").getDeclaredClasses()[0].getMethod("a", String.class).invoke(null, "{\"text\": \"" + text + "\"}");

            Constructor<?> titleConstructor = getNMSClass("PacketPlayOutTitle").getConstructor(getNMSClass("PacketPlayOutTitle").getDeclaredClasses()[0], getNMSClass("IChatBaseComponent"), int.class, int.class, int.class);
            Object packet = titleConstructor.newInstance(getNMSClass("PacketPlayOutTitle").getDeclaredClasses()[0].getField(subtitle ? "SUBTITLE" : "TITLE").get(null), chatTitle, 5, 20, 5);

            sendPacket(player, packet);
            return true;
        } catch (Exception e) {
            // incompatible version
            SpleefMain.getInstance().log(Level.SEVERE, "Could not access NMS classes. Please use a plugin version which is compatible with your server version for full functionality.");
            e.printStackTrace();
            nmsFailed = true;
            return false;
        }
    }

    private static void sendPacket(Player player, Object packet) throws Exception {
        try {
            Object handle = player.getClass().getMethod("getHandle").invoke(player);
            Object playerConnection = handle.getClass().getField("playerConnection").get(handle);
            playerConnection.getClass().getMethod("sendPacket", getNMSClass("Packet")).invoke(playerConnection, packet);
        } catch (Exception e) {
            throw e;
        }
    }

    private static Class<?> getNMSClass(String name) throws Exception {
        try {
            return Class.forName("net.minecraft.server" + Bukkit.getServer().getClass().getPackage().getName().split("\\.")[3] + "." + name);
        } catch (ClassNotFoundException e) {
           throw e;
        }
    }

}