Technique: Simple enum and retrieve/reverse lookup using valueOf() public class OrderService { // Note : enums can be defined in its own file or inside a class if they are only relevant with it. public enum Status { PROCESSING, SHIPPED, COMPLETED; } public void update(long orderId, Status status) { // something } } // import static OrderService.Status; // import static OrderService.Status.* ; // OrderService service = new OrderService(); // service.update(100L, SHIPPED); // use enum // Status status = Status.valueOf("SHIPPED"); // reverse lookup by constant, throws IllegalArgumentException if no match. // System.out.println ( status.toString() ); // prints value - SHIPPED Technique: Stores enum constant and value in a map, retrieve/reverse lookup using fromValue() public enum Status { PROCESSING("processing"), SHIPPED("shippin...