MultiSet

Google collection のMultiSet → 統計処理に便利

      Multiset<String> counter = ConcurrentHashMultiset.create();

      counter.add("Red");
      counter.add("Blue",2);
      counter.add("Red",3);
      counter.add("Green");
      counter.add("Red");

      //Set<String> colors = counter.elementSet();

      for(Iterator<String> it=counter.elementSet().iterator();it.hasNext();){
         String color = it.next();
         System.out.println(color+"-->"+counter.count(color));
      }