Stop shop updater when server is empty and restart on join

src/main/java/de/epiceric/shopchest/ShopChest.java

@@ -402,6 +402,13 @@ public class ShopChest extends JavaPlugin {
         return updater;
     }
 
+    /**
+     * Set the {@link ShopUpdater} that schedules hologram and item updates
+     */
+    public void setUpdater(ShopUpdater updater) {
+        this.updater = updater;
+    }
+
     /**
      * @return Whether the plugin 'Towny' is enabled
      */

src/main/java/de/epiceric/shopchest/listeners/ShopUpdateListener.java

@@ -3,6 +3,7 @@ package de.epiceric.shopchest.listeners;
 import de.epiceric.shopchest.ShopChest;
 import de.epiceric.shopchest.event.ShopUpdateEvent;
 import de.epiceric.shopchest.shop.Shop;
+import de.epiceric.shopchest.utils.ShopUpdater;
 import org.bukkit.Bukkit;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
@@ -27,6 +28,11 @@ public class ShopUpdateListener implements Listener {
 
     @EventHandler(priority = EventPriority.MONITOR)
     public void onPlayerJoin(PlayerJoinEvent e) {
+        if (!plugin.getUpdater().isRunning()) {
+            plugin.setUpdater(new ShopUpdater(plugin));
+            plugin.getUpdater().start();
+        }
+
         for (Shop shop : plugin.getShopUtils().getShops()) {
             if (shop.getHologram() != null) shop.getHologram().hidePlayer(e.getPlayer());
             if (shop.getItem() != null) shop.getItem().setVisible(e.getPlayer(), false);

src/main/java/de/epiceric/shopchest/utils/ShopUpdater.java

@@ -34,9 +34,17 @@ public class ShopUpdater extends Thread {
         super.interrupt();
     }
 
+    public boolean isRunning() {
+        return running;
+    }
+
     @Override
     public void run() {
         while(running) {
+            if (Bukkit.getOnlinePlayers().isEmpty()) {
+                cancel();
+            }
+
             long timeNow = System.currentTimeMillis();
             long timeElapsed = timeNow - lastTime;