Count the number of items in my array list

I want to count the number of itemids in my array, can i get an example of how i would go about adding this to my code. code below;

if (value != null && !value.isEmpty()) {
    Set set = value.keySet();
    Object[] key = set.toArray();
    Arrays.sort(key);

    for (int i = 0; i < key.length; i++) {
        ArrayList list = (ArrayList) value.get((String) key[i]);

        if (list != null && !list.isEmpty()) {
            Iterator iter = list.iterator();
            double itemValue = 0;
            String itemId = "";

            while (iter.hasNext()) {
                Propertyunbuf p = (Propertyunbuf) iter.next();
                if (p != null) {
                    itemValue = itemValue + p.getItemValue().doubleValue();
                    itemId = p.getItemId();
                }

                buf2.append(NL);
                buf2.append("                  " + itemId);

            }

            double amount = itemValue;
            totalAmount += amount;
        }
    }
}

Solution 1:

The number of itemIds in your list will be the same as the number of elements in your list:

int itemCount = list.size();

However, if you're looking to count the number of unique itemIds (per @pst) then you should use a set to keep track of them.

Set<String> itemIds = new HashSet<String>();

//...
itemId = p.getItemId();
itemIds.add(itemId);

//... later ...
int uniqueItemIdCount = itemIds.size();

Solution 2:

You want to count the number of itemids in your array. Simply use:

int counter=list.size();

Less code increases efficiency. Do not re-invent the wheel...