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Sorting map keys by comparing it's values

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This demonstrate the expressiveness of Groovy vs Java.

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  1. import java.util.*;
  2.  
  3. //
  4. // Groovy version of "Sort keys by values" is:
  5. //    keys.sort{ lang[it] }
  6. // That's one line replacement!!!
  7. //
  8.  
  9. class MapSort {
  10. 	public static void main(String[] args){
  11. 		Map lang = new HashMap();
  12. 		lang.put(0, "Java");
  13. 		lang.put(1, "Groovy");
  14. 		lang.put(2, "Ruby");
  15. 		lang.put(3, "Python");
  16. 		lang.put(4, "C#");
  17. 		lang.put(5, "C++");
  18. 		lang.put(6, "Perl");
  19.  
  20. 		List keys = new ArrayList(lang.keySet());
  21.  
  22. 		//Sort keys by values.
  23. 		final Map langForComp = lang;
  24. 		Collections.sort(keys, 
  25. 			new Comparator(){
  26. 				public int compare(Object left, Object right){
  27. 					Integer leftKey = (Integer)left;
  28. 					Integer rightKey = (Integer)right;
  29.  
  30. 					String leftValue = (String)langForComp.get(leftKey);
  31. 					String rightValue = (String)langForComp.get(rightKey);
  32. 					return leftValue.compareTo(rightValue);
  33. 				}
  34. 			});
  35.  
  36. 		//List the key value
  37. 		for(Iterator i=keys.iterator(); i.hasNext();){
  38. 			Object k = i.next();
  39. 			System.out.println(k + " " + lang.get(k));
  40. 		}
  41. 	}
  42. }

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