JSF Standard Converters
The JavaServer Faces provides a set of Converters. You can use that to convert component data. The purpose of conversion is to take the String-based data from the Servlet API and convert it to strongly typed Java objects.
The javax.faces.convert package contains all the standard converters. Converters are implicitly assigned based on the type of the EL expression pointed to by the value of the component. You can also access these converters by converter ID. The following table shows converter classes and their associated converter IDs.
A standard error message is associated with each of the converters. If you are using any converter onto a component on your page and the converter is not able to convert the component's value, the converter's error message will display on the page.
The standard converters DateTimeConverter and NumberConverter both have their own tags, which allow you to configure the format of the component data by using the tag attributes.
JSF Data-Conversion Core Tags
JSF <f:converter> Tag Example
// index page
// response page