PlayerListener.java

package net.arcoria.rpgcraft;

import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.inventory.InventoryClickEvent;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.inventory.Inventory;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.PlayerInventory;
import org.bukkit.Material;
import org.bukkit.event.Cancellable;

public class PlayerListener implements Listener {

    @EventHandler
    public void onPlayerJoin(PlayerJoinEvent e) {
        Player player = e.getPlayer();
        player.sendMessage("Welcome, " + player.getName() + "!");
        Inventory inv = player.getInventory();
        inv.setItem(0, new ItemStack(Material.CHEST, 1));
    }
    @EventHandler
    public void InventoryClick(InventoryClickEvent event){
        if (event.getInventory() instanceof PlayerInventory) {
            if (event.getRawSlot()==0) {
                event.setCancelled(true);
            }

        }
    }

}