Map myMapl new Hash Map Hash Map myMap2 new Hash Map

Which is better?

Conventional wisdom says that you should prefer Map, because it allows you to change the underlying implementation to anything that implements the Map interface. Conventional wisdom is correct for conventional programming, but isn't so great for embedded systems. Calling through an interface reference can take 2x longer than a virtual method call through a concrete reference.

If you have chosen a HashMap because it fits what you're doing, there is little value in calling it a Map. Given the availability of IDEs that refactor your code for you, there's not much value in calling it a Map even if you're not sure where the code is headed. (Again, though, public APIs are an exception: a good API usually trumps small performance concerns.)

0 0

Post a comment