How to sort HashMap entries in alphabetic order?

Question

I have made a program which will read in text from the user, and then display the letter frequencies of the user's text. I am experimenting with hashmaps and I am not sure how to display my results in alphabetical order.

I currently have:

Map<Character, Integer> map = new HashMap<Character, Integer>();    
for (int i = 0; i < user.length(); i++) {
  Integer count = map.get(user.charAt(i)); // if not in map
  if (count == null)
    map.put(user.charAt(i), 1);
  else
    map.put(user.charAt(i), count + 1);
}

As my code for storing the values, but when I print the result

System.out.println(map.entrySet());

I get [a=1, r=2, h=1, y=1]. (For printing "Harry")

score 2 · Accepted Answer · edited May 23 '17 at 11:44

2

What you're looking for is a collection that would implement the SortedMap interface. Try using TreeMap, which guarantees the natural ordering of its keys.

This question describes differences between various implementations of Map: Difference between HashMap, LinkedHashMap and TreeMap

edited May 23 '17 at 11:44

Community

1
1

answered Mar 22 '15 at 12:36

AtomHeartFather

954
17
35

score 1 · Answer 2 · answered Mar 22 '15 at 12:28

1

Use TreeMap instead of HashMap.

answered Mar 22 '15 at 12:28

davide

1,918
2
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How to sort HashMap entries in alphabetic order?

2 Answers2