A simple Java Configuration class to provide some easy configuration capabilities to any Java project.

Configuration.java

/**
 * This `Configuration` class load properties from `res/configuration.properties` file.
 * some provided helpers will retrieve:
 * - String value `Configuration.get(String key, String default)`
 * - int value `Configuration.getInteger(String key, inf default)`
 * - float value `Configuration.getFloat(String key, float default)`
 *
 * @author McGivrer
 * @see https://gist.github.com/McGivrer
 * @see https://twitter.com/McGivrer
 */
static class Configuration {
	private static final String UNKNOWN_CONFIG_KEY = "UNKNOWN_CONFIG_KEY";
	public static Configuration instance = new Configuration();
	Properties props;

	private Configuration() {
		props = new Properties();
		reload();
	}

	/**
	 * Load configuration from `/res/configuration.properties` file.
	 */
	private void load() {
		try {
			props.load(Game.class.getResourceAsStream("/res/configuration.properties"));
		} catch (IOException e) {
			System.err.println("Unable to read configuration file");
			System.exit(-1);
		}
	}

	/**
	 * retrieve a value from configuraiton.properties file.
	 * 
	 * @param key
	 *            key configuration to be retrieved.
	 * 
	 * @return String value
	 */
	private String getConfig(String key) {
		if (props.containsKey(key)) {
			return props.getProperty(key);
		} else {
			return UNKNOWN_CONFIG_KEY;
		}
	}

	/**
	 * retrieve a <code>int</code> value for configuration <code>key</code>.
	 * 
	 * @param key
	 * @return
	 */
	public static int getInteger(String key, int defaultValue) {
		String value = Configuration.instance.getConfig(key);
		if (value.equals(UNKNOWN_CONFIG_KEY)) {
			return defaultValue;
		}
		return Integer.parseInt(value);
	}

	/**
	 * retrieve a <code>float</code> value for configuration <code>key</code>.
	 * 
	 * @param key
	 * @return
	 */
	public static float getFloat(String key, float defaultValue) {
		String value = Configuration.instance.getConfig(key);
		if (value.equals(UNKNOWN_CONFIG_KEY)) {
			return defaultValue;
		}
		return Float.parseFloat(value);
	}

	/**
	 * retrieve a <code>String</code> value for configuration <code>key</code>.
	 * 
	 * @param key
	 * @return
	 */
	public static String get(String key, String defaultValue) {
		String value = Configuration.instance.getConfig(key);
		if (value.equals(UNKNOWN_CONFIG_KEY)) {
			return defaultValue;
		}
		return value;
	}

	/**
	 * request a configuration reload from file.
	 */
	public static void reload() {
		Configuration.instance.load();
	}
}