Long switch statement to lookup fifty-something commands
Giant switch statements are a code smell.  In Java, the usual remedy is to refactor using the Replace Conditional with Polymorphism recipe.

However, I think your problem runs even deeper.  I raise the following objections:


Why should this code exist at all?  Shouldn't getCommand(commandType, agentId); just return the appropriate result for all values of commandType?  Or are there specific command types that you want to disable?  The latter possibility seems disturbing.  If this code is, say, part of a permission-checking system to allow only certain types of commands, I would say that the permission-checking system is woefully underdeveloped.
Why does getCommand(…) return a String?  What use could a constant-to-string translation possibly have?


I wish I could give you more constructive suggestions, but unfortunately, you haven't presented much context in the question to allow a deeper analysis.