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Calculate The Second Highest Frequency

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Calculate The Second Highest Frequency
Write a method that accepts a String and returns the character with the second highest frequency. For example "aabbbc" would return 'a'. If the string contains spaces, they can be disregarded from the count.

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  1. import java.util.ArrayList;
  2. import java.util.Collections;
  3. import java.util.Comparator;
  4. import java.util.HashMap;
  5. import java.util.List;
  6. import java.util.Map;
  7.  
  8. public class FrequencyFinder {
  9.  
  10. 	public static void main(String[] args) {
  11. 		String str = "aaabbbaaacccc     aaaaddddd";
  12. 		findSecondHighestFreq(str);
  13. 	}
  14.  
  15. 	private static char findSecondHighestFreq(String inStr) {
  16. 		char secondChar = 0;
  17. 		Map<Character, Integer> charMap = new HashMap<Character, Integer>();
  18. 		scanChar(inStr.toCharArray(), charMap);
  19.  
  20. 		List<Map.Entry<Character,Integer>> entryList = new ArrayList<Map.Entry<Character,Integer>>(charMap.entrySet());
  21. 		Collections.sort(entryList, 
  22. 				new Comparator<Map.Entry<Character,Integer>>() {
  23. 			public int compare(Map.Entry<Character,Integer> a, Map.Entry<Character,Integer> b) {
  24. 				return b.getValue().compareTo(a.getValue());
  25. 			}
  26. 		});
  27.  
  28. 		System.out.println("2nd most freq: key="+entryList.get(1).getKey()+", count="+entryList.get(1).getValue());
  29.  
  30. 		return secondChar;
  31. 	}
  32.  
  33. 	private static void scanChar(char[] inCharArr, Map<Character, Integer> charMap) {
  34. 		for (char chLocal : inCharArr) {
  35. 			if (chLocal==' ') {
  36. 				// ignore space character
  37. 				continue;
  38. 			}
  39. 			if (!charMap.containsKey(chLocal)){
  40. 				charMap.put(chLocal, 1);
  41. 			} else {
  42. 				charMap.put(chLocal, (charMap.get(chLocal)+1));
  43. 			}
  44. 		}
  45. 	}
  46.  
  47. }

URL: http://java.dzone.com/articles/thursday-code-puzzler-second

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