Create your messages_en.properties with your messages as a key value pair
greeting_hello=Hello {0}
Now in code use the following
ResourceBundle resourceBundle= PropertyResourceBundle.getBundle("messages_en.properties");
String message = resourceBundle.getString("greeting_hello");
MessageFormat messageFormat = new MessageFormat(message);
String formattedMessage = messageFormat.format("Markzi");
System.out.println(formattedMessage);
This will print out Hello Markzi