public static boolean getBoolean(String key, boolean def) {
		if (key == null) {
			throw new NullPointerException("key");
		}

		String value = props.getProperty(key);
		if (value == null) {
			return def;
		}

		value = value.trim().toLowerCase();
		if (value.length() == 0) {
			return true;
		}

		if (value.equals("true") || value.equals("yes") || value.equals("1")) {
			return true;
		}

		if (value.equals("false") || value.equals("no") || value.equals("0")) {
			return false;
		}

		// "Unable to parse the boolean system property '" + key + "':" + value + " - "
		// "using the default value: " + def);
		return def;
	}