How can I sort values of a Map in Java using its key

Question

I have a Map in java that has strings for key as well as value.

Data is like following: <"Ram", "1">, <"Johny", "1">, <"Humber", "4">

I want to sort the map based on its keys. So, In the end, I will have Johny, Humber, Ram

Eventually, I am trying to get two strings out of this Map. First String: in alphabetical order and Second String: Answers (in the same order as the question).

Right now I have the following:

Iterator itr = paramMap.entrySet().iterator();
while (itr.hasNext()) {
Map.Entry pair = (Map.Entry)itr.next();
 questionAnswers += pair.getKey()+",";
}

This gets me the questions in a string but they are not in order.

Answer 1

Use a TreeMap. This is precisely what it is used for.

If this map is passed to you and you cannot determine the type, then you can do the following:

SortedSet<String> keys = new TreeSet<>(maps.keySet());
for (String key : keys) { 
   String value = maps.get(key);
   // do something
}

This will iterate across the map in natural order of the keys.

Answer 2

Assuming TreeMap is not good for you (and assuming you can't use generics):

List sortedKeys=new ArrayList(yourMap.keySet());
Collections.sort(sortedKeys);
// Do what you need with sortedKeys.