JSTL Formatting <fmt:parseNumber> Tag

In JSTL, the <fmt:parseNumber> tag is mainly used to parse the numeric string into the numeric format. This allows the developers to properly and efficiently convert the string representation of a number into an actual numeric type.

This also provides control over the locale-specific formatting.
This tag can also be used for handling the user input or for external number values that need to be processed in a standard format.

In this article, we will see the Syntax along with parameters, attributes of this tag, and also the practical implementation.

Syntax of <fmt:parseNumber> Tag

The below code is the syntax for parsing a number in JSTL

<fmt:parseNumber var="resultVar" value="numericString" 
                       [type="numberType"] 
                       [pattern="formatPattern"]
/>

Where,

var: This is the variable to store the parsed numeric result.
value: This is the numeric string to be parsed. It can be a specific string or the user input string.
type: This is the optional parameter, which is a type of number to parse. Types are numbers or currency.
pattern: This is the optional parameter, which is the format pattern for parsing. This is used in custom formats.

Attributes of <fmt:parseNumber> Tag

The table below describes the attributes present in <fmt:parseNumber> with proper description.

Attribute	Description	Required	Default
value	This is the numeric string which is to be parsed	Yes	N/A
type	This is the type of number to parse. Can be a number or currency	No	number
parseLocale	The locale to be used for parsing	No	Default Locale
interferon	This attribute indicates whether only integer values should be parsed	No	false
pattern	This is the format pattern for parsing the custom formats.	No	N/A
timeZone	time zone to be used for parsing the provided time	No	Default time zone
var	The variable in which the parsed result will be stored	Yes	N/A
scope	This is the scope of variables like page, request, session, and application.	No	page

Example JSTL Formatting <fmt:parseNumber> Tag

In this example, we will discuss the example for parseNumber using <fmt:parseNumber>

HTML

<%@ page contentType="text/html;charset=UTF-8" language="java" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> 

<html> 

  <head> 

      <title>JSTL fmt:parseNumber Example</title> 

  </head> 

  <body> 

    <c:set var="numericString" value="1,234.56"/> 

    <h3>Original Number (String Format): ${numericString}</h3> 

    <fmt:parseNumber var="parsedNumber"

                     value="${numericString}"

                     type="currency"

                     parseLocale="en_US"

                     integerOnly="true"

                     pattern="#,###.##"

                     scope="request"/> 

    <h3>Parsed Number (Integer Only): ${parsedNumber}</h3> 

  </body> 

</html>

Output:

Original Number (String Format): 1,234.56
Parsed Number (Integer Only): 1234

Output of the JSTL <fmt:parseNumber> Tag Program:

Explanation of the above Program:

Firstly, have set the numericString variable with the value as “1234.56“. This is the string format value that will be parsed.
Then by using the <fmt:parseNumber> tag, we have parsed the numeric string with various attributes.
The parsed number is then stored in the parsed number variable win the request scope.
Also, we have set the attribute intergerOnly = true. This is the return of the absolute number without any decimals.
We are lastly, showing the output using ${parsedNumber} an <h3> tag of HTML.

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