How do I iterate over each Entry in a Map?

If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it, what is the most efficient way of going through the map?

traditional for loop vs Iterator in Java

Is there any performance testing results available in comparing traditional for loop vs Iterator while traversing a ArrayList,HashMap and other collections?

java: concurrent collections

I'm trying to find one or more concurrent collections to use that I can implement the following behavior (the names are contrived for analogy purposes):