ConfigLib

public final class Example {
    // * To create a configuration annotate a class with @Configuration and make sure that
    //   it has a no-args constructor.
    // * Now add fields to that class and assign them default values.
    // * That's it! Fields can be private; setters are not required.
   @Configuration
    public static class BaseConfiguration {
        private String host = "127.0.0.1" ;
        private int port = 1234 ;
        // The library supports lists, sets, and maps.
        private Set <String > blockedAddresses = Set. of ( "8.8.8.8" ) ;
        // Fields can be ignored by making them final, transient, static or by
        // annotating them with @Ignore.
        private final double ignoreMe = 3.14 ;
    }

    // This library supports records; no @Configuration annotation required
    public record User (
            String username,
           @Comment ( "Please choose a strong password." )
            String password
    ) { }

    // Subclassing of configurations and nesting of configurations in other configurations
    // is also supported. Subclasses don't need to be annotated again.
    public static final class UserConfiguration extends BaseConfiguration {
        // You can add comments with the @Comment annotation. Each string in the comment
        // array is written (as a comment) on a new line.
       @Comment ( { "The admin user has full access.", "Choose a proper password!" } )
       User admin = new User ( "root", "toor" ) ; // The User class is a record!
       List <User > blockedUsers = List. of (
                new User ( "user1", null ), // null values are supported
                new User ( "user2", null )
        ) ;
    }

    public static void main ( String [ ] args ) {
       var configFile = Paths. get ( "/tmp/config.yml" ) ;
       var config = new UserConfiguration ( ) ;

        // Save a new instance to the configuration file
       YamlConfigurations. save (configFile, UserConfiguration. class, config ) ;

        // Load a new instance from the configuration file
       config = YamlConfigurations. load (configFile, UserConfiguration. class ) ;
        System. out. println (config. admin. username ) ;
        System. out. println (config. blockedUsers ) ;

        // Modify and save the configuration file
       config. blockedUsers. add ( new User ( "user3", "pass3" ) ) ;
       YamlConfigurations. save (configFile, UserConfiguration. class, config ) ;
    }
}

host : 127.0.0.1
port : 1234
blockedAddresses :
 - 8.8.8.8
# The admin user has full access.
# Choose a proper password!
admin:
  username : root
  # Please choose a strong password.
  password : toor
blockedUsers:
  - username : user1
  - username : user2
  - username : user3
    password : pass3