Replace Ifs using design Pattern

Question

Hi Guys,
I have an class that receives an error code and set an error message associated. So, to avoid nested ifs, im looking for a solution maibe using a Pattern.
if(returncode.equals("052")){
     errors.add("error", new ActionError("error.msg", applicationResources.getMessage("errors.myerror52")));
if(returncode.equals("055")){
     errors.add("error", new ActionError("error.msg", applicationResources.getMessage("errors.myerro55")));
For each new errorCode and your respective message, i need to add a new if in the class....
I accept some suggestions to make this better !!
Thanks a lot !

Answer 1

There are a number of approaches you could take. The validity and relative merits of some of them depend on whether the return code is truly a string, or a number that's formatted as a string; on whether you are always simply calling errors.add(), just with different arguments, or if you need to take completely different actions in some cases; on how many return codes there are; on how often codes will be added, changed, or removed.
1. A Map from return code --> object encapsulating the args to errors.add()
2. Command Pattern, which might be realized as a Map of return code --> instance of a class implementing how to handle that code, or return code --> Class object or class name, which then gets instantiated and the new object executed. In either case, the object that does the processing will implement some interface that you define.
3. An array whose index is the return code and whose value is an object, Class object, or class name that handles that particular code.
4. An enum, with each enum value having either a different set of fields to be passed to errors.add() or a different implementation of a method, if you don't simply call errors.add() for each code.
5. A switch statement on the return code, either as an int or as an enum, or, if you're on Java 7, as a String.
Somewhat independently of which of the above approaches you take, you need to decide whether you will hardcode the code --> action mapping, or if you want to put it in a config file or database.