[collection.containskey] When to use map.containsKey

The containsKey(Object key) method on a Map need only be used when it is not intended to try and retrieve a value from the map.  If key is not in the collection, a get call will return null anyway.

In the above example, the mobileRenderingProfiles map is massive, so the containsKey( ) call may take a non-trivial amount of time to find the data it seeks.

Yet, it is followed almost immediately by a get( ) call, which will do an almost identical search to find the same item in the map.

A better way would be as below.  

Thus an additional lookup in the map is saved and the code is a little simpler.