Formatting Number with fmt:formatNumber Action

JSTL provides you the to format number in different forms. If you remember, with the action you can print any number such as integer or floating-point number. But with you have more controls how number is formatted and printed. The most simple basic usage of the action is as follows:

The action accepts any number in the value attribute. It does more than the action that it formats the number based on the locale which specify by the web browser setting in the client side or set by the web application in the server side. Let's take a look at an example of using :

In the above example, first we define a variable and set its value to 200.51. Then we  use action to override the locale of the browser. We set the locale to en_US so when we use the action  to format the number therefore it displays as 200.51 which is USA format. Next we set the locale to fr_FR and print the number again, now it displays as 200,51 which is France format.

Let's take a look at attributes of the in more details:

Name	Meaning
value	Numeric value to be formatted.
type	Determine the value is formatted as number, currency, or percentage.
pattern	Specify a custom formatting pattern for the output.
currencyCode	Only apply for the currency formatting which accepts ISO 4217currency code.
currencySymbol	Only apply for the currency formatting, accepts currency symbol
groupingUsed	Used to define grouping separator for formated number
maxIntegerDigits	Specify the maximum number of digits in the integer portion of the formatted number in the output.
minIntegerDigits	Specify the minimum number of digits in the integer portion of the formatted number in the output.
maxFractionDigits	Specify the maximum number of digits in the fractional portion of the formatted number in the output
minFractionDigits	Specify the minimum number of digits in the fractional portion of the formatted number in the output.
var	The variable name of the exported scoped variable
scope	scope of the var variable

 Printing the percentage

Let's play with the printing percentage value.

In order to print the percentage format, you assign percent to the type attribute of the action.

Printing different currency locale  To print currency, you assign currency to the type attribute and set the locale before outputting the formatted number.

Printing number with a custom pattern Sometimes, you'll need to print number with a specific custom pattern especially number inscientific notation. In these cases, you can define your own pattern and specify it in thepattern attribute of the action. Let's take a look at an example of printing a big number with a scientific pattern:

If you run the above code you will see the number is formatted as the pattern which is46.5637E9 .

There are a lot more cases you'll need to format number and output it on screen. You can refer to the attribute table above to find what you need and exercise with it to get more familiar with different kind number formatting.