private void ensureCategoryIndexMap() {
        if (categories.isEmpty() || !categoryIndexMap.isEmpty()) {
            return;
        }

        int pos = 0;
        for (String cat : categories) {
            final int catCount = categoryCounts.get(cat);
            categoryIndexMap.put(cat, pos);
            pos += catCount + 1;
        }
    }
gets number of content entries in the list
main/src/main/java/cgeo/geocaching/utils/CategorizedListHelper.java