Main.java - SignCommands

package com.thebukkitarea.signcommands;

import org.bukkit.block.Sign;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.block.Action;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.plugin.java.JavaPlugin;

import java.util.*;

public class Main extends JavaPlugin implements Listener {

    private HashMap<Integer, String> signCommands = new HashMap<Integer, String>();

    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);

        for (Map.Entry<String, Object> entry : getConfig().getValues(false).entrySet()) {
            int id;

            try { id = Integer.parseInt(entry.getKey()); }
            catch (NumberFormatException ex) { continue; }

            signCommands.put(id, String.valueOf(entry.getValue()));
        }
        saveConfig();
    }

    @EventHandler
    public void onSignClick(PlayerInteractEvent event) {
        if (event.getAction() == Action.RIGHT_CLICK_BLOCK && event.getClickedBlock().getState() instanceof Sign) {
            Sign sign = (Sign) event.getClickedBlock().getState();
            if (sign.getLine(0).equalsIgnoreCase("[command]")) {
                int id;

                try { id = Integer.parseInt(sign.getLine(1)); }
                catch (NumberFormatException ex) { return; }

                String cmd;
                if ((cmd = signCommands.get(id)) != null)
                    event.getPlayer().performCommand(cmd);
            }
        }
    }
}