JSF validation pattern for input control


I have a JSF page and I have a inputtext in this page. I take the user keywords form this inputtext. My problem is that I want to control the number of keywords that the user enter(they separated by "-" ) and check them to not to be more than a specific number. is there any validation pattern or any better way to check them?


You can do this validation by using a <a href="http://www.mkyong.com/jsf2/custom-validator-in-jsf-2-0/" rel="nofollow">Custom Validator</a>, by defining a java class implementing Validator interface, which should performs the specific desired validation. Here's a small example that shows when the user types keywords (separated by "-") more than a predetermined max limit (e.g 5), a validation message pops up when passing to the next field :

<strong>View :</strong> index.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:f="http://java.sun.com/jsf/core" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>Custom Validator Example</title> </h:head> <h:body> <h:form> <h:panelGrid columns="3"> Give strings separated by "-" : <h:inputText id="input" size="30" required="true" requiredMessage="Field required" value="#{myBean.myExpression}"> <f:ajax event="blur" render="inputMessage" /> <f:validator binding="#{myValidator}" /> </h:inputText> <h:message for="input" id="inputMessage" style="color:red" /> Enter your name: <h:inputText id="input1" required="true" requiredMessage="missed name" value="#{myBean.name}" /> </h:panelGrid> </h:form> </h:body>

<strong>A simple managed-bean :</strong> MyBean.java

// imports @ManagedBean @RequestScoped public class MyBean implements Serializable { private String myExpression ; private String name ; // getters/setters }

<strong>Custom Validator :</strong> MyValidator.java

// imports @ManagedBean @ViewScoped public class MyValidator implements Validator { @Override public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException { int max_limit = 5; // for example String expression = (String) value; String[] result = expression.split("-"); int count=0; for(int i=0;i<result.length;i++){ if (result[i].equals("")) continue; // Empty keywords (e.g successive "-" caracters) are ignored. Else, just omit this line count++; } if (count > max_limit) { FacesMessage facesmsg = new FacesMessage(FacesMessage.SEVERITY_ERROR,"Exeeded allowed limit !",null); throw new ValidatorException(facesmsg); } } }


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