java enum string matching

Question

I have an enum as follows:

public enum ServerTask {

HOOK_BEFORE_ALL_TASKS("Execute"),
COPY_MASTER_AND_SNAPSHOT_TO_HISTORY("Copy master db"),
PROCESS_CHECKIN_QUEUE("Process Check-In Queue"),
...
}

I also have a string (lets say string = "Execute") which I would like to make into an instance of the ServerTask enum based on which string in the enum that it matches with. Is there a better way to do this than doing equality checks between the string I want to match and every item in the enum? seems like this would be a lot of if statements since my enum is fairly large

Answer 1

At some level you're going to have to iterate over the entire set of enumerations that you have, and you'll have to compare them to equal - either via a mapping structure (initial population) or through a rudimentary loop.

It's fairly easy to accomplish with a rudimentary loop, so I don't see any reason why you wouldn't want to go this route. The code snippet below assumes the field is named friendlyTask.

public static ServerTask forTaskName(String friendlyTask) {
    for (ServerTask serverTask : ServerTask.values()) {
        if(serverTask.friendlyTask.equals(friendlyTask)) {
            return serverTask;
        }
    }
    return null;
}

The caveat to this approach is that the data won't be stored internally, and depending on how many enums you actually have and how many times you want to invoke this method, it would perform slightly worse than initializing with a map.

However, this approach is the most straightforward. If you find yourself in a position where you have several hundred enums (even more than 20 is a smell to me), consider what it is those enumerations represent and what one should do to break it out a bit more.