The Java EE 5 Tutorial

Displaying Error Messages

A message tag is used to display error messages on a page when data conversion or validation fails after the user submits the form. The message tag in greeting.jsp displays an error message if the data entered in the field does not comply with the rules specified by the LongRangeValidator implementation, whose tag is registered on the text field component.

The error message displays wherever you place the message tag on the page. The message tag’s style attribute allows you to specify the formatting style for the message text. Its for attribute refers to the component whose value failed validation, in this case the userNo component represented by the inputText tag in the greeting.jsp page.

Put the message tag near the end of the page:

<%@ taglib uri="" prefix="h" %>
<%@ taglib uri="" prefix="f" %>
    <h:form id="helloForm1">
        <h2>Hi. My name is Duke. I’m thinking of a number from
         <h:outputText lang="en_US"
             value="#{UserNumberBean.minimum}"/> to
         <h:outputText value="#{UserNumberBean.maximum}"/>.
        Can you guess it?</h2>
        <h:graphicImage id="waveImg" url="/" />
        <h:inputText id="userNo" label="User Number"
                     maximum="#{UserNumberBean.maximum}" />
        <h:commandButton id="submit"
             action="success" value="Submit" />
        <h:message showSummary="true" showDetail="false"
                style="color: red;
                 font-family: ’New Century Schoolbook’, serif;
                 font-style: oblique;
                 text-decoration: overline"

Now you have completed the greeting page. Assuming you have also done the response.jsp page, you can move on to defining the page navigation rules.