JavaServer Pages, 3rd Edition

Number Formatting

Unless the shopping cart is empty, a second <c:forEach> action generates a list of the contents as an HTML table with the name and price of each product. A thing to note here is the use of the <fmt:formatNumber> action:

<fmt:formatNumber value="${product.price}" 
  type="currency" />

This is an action from the JSTL I18N formatting library, declared by the second taglib directive at the top of the page. It formats the number specified by the value attribute as defined by other attributes, such as the type attribute used here. The currency type tells it to format the number according to default rules for currency values. Other attributes not used here let you define specific rules for the number of decimals to show, where to put number-grouping characters, prefix and suffix, etc. The number is formatted according to the rules for a specific geographical, political, or cultural region, known as a locale. A locale defines things such as which characters to use as a decimal separator, thousand grouping, and currency symbol. Locales and all JSTL formatting actions are discussed in detail in Chapter 14, but to give you an idea of how formatting varies between regions, here’s an example of the number 10000.00 formatted as currency for USA, Sweden, and Italy:

USA

$10,000.00

Sweden

10 000,00 kr

Italy

L. 10 000

In Example 10-6, the <fmt:formatNumber> action formats the price information for each product and the total for everything in the cart.