Sorted keys from HashMap

[S Thiyanesh]

To retrieve the keys of a HashMap in sorted order,
1.Copy the contents of HashMap to TreeMap.
2.Add the keys the keys of HashMap to TreeSet
3.Pass the HashMap to Arrays.sort
4.Pass the HashMap to Collections.sort

This question is in Whizlabs Diagnostic test.

Can anyone give the answer with explanation

[Ashish Laddha]

To retrieve the keys of a HashMap in sorted order,
1.Copy the contents of HashMap to TreeMap.
2.Add the keys the keys of HashMap to TreeSet
3.Pass the HashMap to Arrays.sort
4.Pass the HashMap to Collections.sort

1. false -> Copying the contents to TreeMap will sort the Map as per the values and not as per the keys
2. true -> When something is added to TreeSet, it is put in ordered manner. So, when keys are put into it, they are ordered
3. false -> This is used to sort the arrays not Map
4. false -> This is used to sort collection (ArrayList, Vector,etc) not Map

[S Thiyanesh]

thanks Ashish

[Garrett Rowe]

1. false -> Copying the contents to TreeMap will sort the Map as per the values and not as per the keys

Thats incorrect. From the documentation of the TreeMap class:

Red-Black tree based implementation of the SortedMap interface. This class guarantees that the map will be in ascending key order, sorted according to the natural order for the key's class (see Comparable), or by the comparator provided at creation time, depending on which constructor is used.