Automatically update config files when changes are made.

Updater.java

import org.bukkit.plugin.java.JavaPlugin;

import javax.xml.bind.annotation.adapters.HexBinaryAdapter;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.security.MessageDigest;

public class Updater implements Runnable {

    private JavaPlugin plugin;

    private MessageDigest digest;
    private File config;

    private String hash;
    private String _hash;

    public Updater(JavaPlugin plugin) {
        this.plugin = plugin;
        plugin.getServer().getScheduler().runTaskTimerAsynchronously(plugin, this, 20L, 20L);
    }

    @Override
    public void run() {
        config = (config != null) ? config : getConfigFile();

        try (InputStream input = new FileInputStream(config)) {
            digest = (digest != null) ? digest : MessageDigest.getInstance("SHA-1");

            byte[] buffer = new byte[(int) config.length()];
            int len = input.read(buffer);

            while (len != -1) {
                digest.update(buffer, 0, len);
                len = input.read(buffer);
            }

            hash = new HexBinaryAdapter().marshal(digest.digest());
        } catch (Throwable thrown) {
            thrown.printStackTrace();
        }

        _hash = (!hash.equals(_hash)) ? update() : hash;
    }

    public File getConfigFile() {
        return new File(plugin.getDataFolder().getPath() + "/config.yml");
    }

    public String update() {
        plugin.reloadConfig();
        return hash;
    }

}