Save User Data in a Text File or a Serialized Object
public class Config {

    private HashMap map;
    Congif(HashMap map) { this.map = map; }

    <T> T get(Class<T> clazz, String key) {
        return (T) map.get(key);
    }

    void put(String key, Serializable value) {
        map.put(key, value);
    }
}