JSF Tutorial - JSF Validate String Length Example








f:validateLength tag is used to validate length of a string value.

We can use the f:validateLength tag as follows. 

<f:validateLength minimum="5" maximum="8" />

Tag Attributes

AttributeDescription
minimuma minimum number of characters
maximuma maximum number of characters

Example

The following code is from UserBean.java.

package com.java2s.common;

import java.io.Serializable;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.SessionScoped;
 
@ManagedBean(name="user")
@SessionScoped
public class UserBean implements Serializable{
  
  String username;

  public String getUsername() {
    return username;
  }

  public void setUsername(String username) {
    this.username = username;
  }

}

The following code is from result.xhtml.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:c="http://java.sun.com/jsp/jstl/core"
      >
    <h:body>
    UserName :  <h:outputText value="#{user.username}" />
    </h:body>
</html>

The following code is from demo.xhtml.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"   
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:c="http://java.sun.com/jsp/jstl/core">
    <h:body>
    <h:form>
      <h:panelGrid columns="3">
        Enter UserName : 
        <h:inputText id="username" value="#{user.username}" 
          size="20" required="true"
          label="UserName" >
          <f:validateLength minimum="5" maximum="10" />
        </h:inputText>
        <h:message for="username" style="color:red" />
      </h:panelGrid>
      <h:commandButton value="Submit" action="result" />
    </h:form>
    </h:body>
</html>


Download Validate_String_Length.zip





To RUN

Copy the generated WAR file from the target folder to Tomcat deployment folder and run Tomcat-Install-folder/bin/startup.bat.

After Tomcat finish starting, type the following URL in the browser address bar. 

http://localhost:8080/simple-webapp/demo.xhtml