Checkpoint

Checkpoint.java

package fr.alaric1001.checkpoint;

import java.util.HashMap;
import java.util.Map;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Location;
import org.bukkit.block.Sign;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.event.block.Action;
import org.bukkit.event.block.SignChangeEvent;
import org.bukkit.event.player.PlayerInteractEvent;
import org.bukkit.event.player.PlayerRespawnEvent;
import org.bukkit.plugin.java.JavaPlugin;

public class Checkpoint extends JavaPlugin implements Listener {
    private final Map<String, Location> checkpoints = new HashMap<String, Location>();

    @Override
    public boolean onCommand(final CommandSender sender, final Command command, final String label, final String[] args) {
        if (command.getName().equalsIgnoreCase("checkpoint") && args.length == 1
                && args[0].equalsIgnoreCase("remove") && sender instanceof Player) {
            checkpoints.remove(sender.getName());
            sender.sendMessage(ChatColor.GREEN + "Checkpoint removed!");
            return true;
        }
        return false;
    }

    @Override
    public void onEnable() {
        super.onEnable();
        Bukkit.getPluginManager().registerEvents(this, this);
    }

    @EventHandler(priority = EventPriority.MONITOR, ignoreCancelled = true)
    public void onPlayerInteract(final PlayerInteractEvent event) {
        if (event.getAction() == Action.RIGHT_CLICK_BLOCK && event.getClickedBlock().getState() instanceof Sign
                && (event.getPlayer().isOp() || event.getPlayer().hasPermission("checkpoint.use"))) {
            final Sign sign = (Sign) event.getClickedBlock().getState();
            if (sign.getLine(0).equals(ChatColor.BLUE + "[CheckPoint]")
                    && sign.getLine(1).equals(ChatColor.BLACK + "Right-click")
                    && sign.getLine(2).equals(ChatColor.BLACK + "to set your")
                    && sign.getLine(3).equals(ChatColor.BLACK + "checkpoint!")) {
                checkpoints.put(event.getPlayer().getName(), event.getPlayer().getLocation());
                event.getPlayer().sendMessage(ChatColor.GREEN + "Checkpoint defined! Use /checkpoint remove to remove it.");
            }
        }
    }

    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
    public void onPlayerRespawn(final PlayerRespawnEvent event) {
        if (checkpoints.containsKey(event.getPlayer().getName()))
            event.setRespawnLocation(checkpoints.get(event.getPlayer().getName()));
    }

    @EventHandler(priority = EventPriority.HIGHEST, ignoreCancelled = true)
    public void onSignChange(final SignChangeEvent event) {
        if (event.getLine(0).equalsIgnoreCase("[CheckPoint]"))
            if (event.getPlayer().isOp() || event.getPlayer().hasPermission("checkpoint.create")) {
                event.setLine(0, ChatColor.BLUE + "[CheckPoint]");
                event.setLine(1, ChatColor.BLACK + "Right-click");
                event.setLine(2, ChatColor.BLACK + "to set your");
                event.setLine(3, ChatColor.BLACK + "checkpoint!");
                event.getPlayer().sendMessage(ChatColor.GREEN + "Checkpoint successfully created!");
            } else {
                event.setLine(0, ChatColor.RED + "[CheckPoint]");
                event.setLine(1, ChatColor.BLACK + "");
                event.setLine(2, ChatColor.BLACK + "");
                event.setLine(3, ChatColor.BLACK + "");
                event.getPlayer().sendMessage(ChatColor.RED + "You're not allowed to do that!");
            }
    }
}

plugin.yml

name: Checkpoint
main: fr.alaric1001.checkpoint.Checkpoint
author: alaric1001
version: 1.2
commands:
    checkpoint:
        description: Main command of Checkpoint.
        aliases: [cp, ckp, chkp, checkp]
        usage: Only one command ATM, /<command> return.

Can I make checkpoint only these two files? I have found many errors when I run these two files.