Avoid using interface member, use concrete collection class instead

        private int mMaxHeightCount = 0;

        private int mMaxWidthCount = 0;

        private final Map<Integer, Integer> mHeightHistogram = new HashMap<Integer, Integer>();

        private final Map<Integer, Integer> mWidthHistogram = new HashMap<Integer, Integer>();

        private final HashMap<Integer, Integer> mHeightHistogram = new HashMap<Integer, Integer>();

        private final HashMap<Integer, Integer> mWidthHistogram = new HashMap<Integer, Integer>();

        private void clearHistogram() {

            mMostCommonKeyHeight = 0;

            mWidthHistogram.clear();

        }

        private static int updateHistogramCounter(Map<Integer, Integer> histogram, Integer key) {

        private static int updateHistogramCounter(HashMap<Integer, Integer> histogram,

                Integer key) {

            final int count = (histogram.containsKey(key) ? histogram.get(key) : 0) + 1;

            histogram.put(key, count);

            return count;