gistfile1.java

protected static void incrementValue(Map<Long, Integer> counters, Long toAdd) {
        Integer currValue = counters.get(toAdd);
        if (currValue == null)
            counters.put(toAdd, 1);
        else
            counters.put(toAdd, currValue+1);
}


Map<String, Integer> counter = new HashMap<String, Integer>();
for (Item item : aa) {
  incrementValue(counter, item.otherattribute.id);
}