4 Example to Iterate over HashMap, Hashtable or any Map in Java

There are multiple ways to iterate, traverse or loop through Map, HashMap, or TreeMap in Java and we are all familiar with either all of those or some of those. But to my surprise, one of my friends was asked in his interview (he has more than 6 years of experience in Java programming) to write code for getting values from hashmap or TreeMap in Java in at least 4 ways. Just like me he was also surprised by this question but written it. I don't know why exactly someone asks this kind of java interview question to a relatively senior java programmer. Though my closest guess is to verify that whether he is still hands-on with coding in java.