Add WorldChange

src/de/steamwar/Teamserver.java

@@ -1,14 +1,24 @@
 package de.steamwar;
 
 import de.steamwar.command.GamemodeCommand;
+import de.steamwar.listener.WorldChange;
+import lombok.Getter;
+import org.bukkit.Bukkit;
 import org.bukkit.plugin.java.JavaPlugin;
 
 public final class Teamserver extends JavaPlugin {
 
+    @Getter
+    private static Teamserver instance;
+
     @Override
     public void onEnable() {
         // Plugin startup logic
+        instance = this;
+
         new GamemodeCommand();
+
+        Bukkit.getPluginManager().registerEvents(new WorldChange(), this);
     }
 
     @Override

src/de/steamwar/listener/WorldChange.java

@@ -0,0 +1,27 @@
+package de.steamwar.listener;
+
+import de.steamwar.Teamserver;
+import org.bukkit.Bukkit;
+import org.bukkit.GameMode;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.EventPriority;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerChangedWorldEvent;
+import org.bukkit.event.player.PlayerJoinEvent;
+
+public class WorldChange implements Listener {
+
+    @EventHandler(priority = EventPriority.HIGHEST)
+    public void onPlayerJoin(PlayerJoinEvent event) {
+        Bukkit.getScheduler().runTaskLater(Teamserver.getInstance(), () -> {
+            event.getPlayer().setGameMode(GameMode.CREATIVE);
+        }, 1L);
+    }
+
+    @EventHandler(priority = EventPriority.HIGHEST)
+    public void onPlayerChangedWorld(PlayerChangedWorldEvent event) {
+        Bukkit.getScheduler().runTaskLater(Teamserver.getInstance(), () -> {
+            event.getPlayer().setGameMode(GameMode.CREATIVE);
+        }, 1L);
+    }
+}