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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		String str = "hello world";
  13.  
  14. 		Map<Character, Integer> lettersCount = new HashMap<>();
  15.  
  16. 		for (int i=0; i <str.length(); i++) {
  17. 			Character current = str.charAt(i);
  18. 			if (Character.isLetter(current)) {
  19. 				Integer previousCount = lettersCount.get(current);
  20. 				if (previousCount != null) {
  21. 					lettersCount.put(current, previousCount + 1);
  22. 				} else {
  23. 					lettersCount.put(current, 1);
  24. 				}
  25. 			}
  26. 		}
  27. 		List<Map.Entry<Character, Integer>> list = new LinkedList<Map.Entry<Character, Integer>>( lettersCount.entrySet() );
  28. 		Collections.sort( list, new Comparator<Map.Entry<Character, Integer>>()
  29.         {
  30.             public int compare( Map.Entry<Character, Integer> o1, Map.Entry<Character, Integer> o2 )
  31.             {
  32.                 return (o2.getValue()).compareTo( o1.getValue() );
  33.             }
  34.         } );
  35. 		for (Map.Entry<Character, Integer> entry : list) {
  36. 			System.out.println(entry.getKey() + " : " + entry.getValue());
  37. 		}
  38. 	}
  39. }
Success #stdin #stdout 0.1s 320512KB
comments (?)
stdin 
Standard input is empty
stdout 
l : 3
o : 2
r : 1
d : 1
e : 1
w : 1
h : 1
https://ideone.com/NN1eWA
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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