300+ [LATEST] Apache Wicket Interview Questions and Answers

Q1. Tell Me The Example Of Username Validation In Apache-wicket?

import org.apache.wicket.validation.CompoundValidator;

import org.apache.wicket.validation.validator.PatternValidator;

import org.apache.wicket.validation.validator.StringValidator;

 public class UsernameValidator extends CompoundValidator {

  private static final long serialVersionUID = 1L;

  public UsernameValidator() {

  add(StringValidator.lengthBetween(6, 15));

add(new PatternValidator(“[a-z0-9_-]+”));



Q2. How To Create Radio Button In Apache-wicket?

//choices in radio button

private static final List TYPES = Arrays.asList(new String[] { “Shared Host”, “VPN”, “Dedicated Server” });

RadioChoice hostingType = new RadioChoice(“hosting”, new PropertyModel(this, “selected”), TYPES);

Q3. How To Create Dropdown Choice In Apache-wicket?


import org.apache.wicket.markup.html.form.DropDownChoice;

//choices in dropdown box

private static final List SEARCH_ENGINES = Arrays.asList(new String[] {

“Google”, “Bing”, “Baidu” });

 //variable to hold the selected value from dropdown box,

//and also make “Google” is selected by default

private String selected = “Google”;

 DropDownChoice listSites = new DropDownChoice(

“sites”, new PropertyModel(this, “selected”), SEARCH_ENGINES);

 //HTML for dropdown box

Q4. How To Keep File Validation In Apache-wicket If No File Has Been Selected?

To fix it, just override the validateOnNullValue() method like this :

FileUploadField fileUpload = new FileUploadField(“fileupload”,new Model());

 fileUpload .add(new AbstractValidator() { 

        public boolean validateOnNullValue(){

        return true;


  protected void onValidate(IValidatable validatable) { 

FileUpload fileUpload = (FileUpload) validatable.getValue();


     protected String resourceKey() {

    return “yourErrorKey”;



Now, when no file is selected, and submit button is clicked, validation will be performed.

Q5. How To Get Servletcontext In Apache-wicket Application?

Yes, you can get the ServletContext class via Wicket’s WebApplication class like this :

import javax.servlet.ServletContext;

import org.apache.wicket.Page;

import org.apache.wicket.protocol.http.WebApplication;

import com.withoutbook.hello.Hello;

 public class CustomApplication extends WebApplication {


public Class getHomePage() {

  ServletContext servletContext = WebApplication.get().getServletContext();

return Hello.class; //return default page



Q6. How To Create Checkbox In Apache-wicket?

final CheckBox chk0 = new CheckBox(“checkbox0”, Model.of(Boolean.TRUE));

 final CheckBox chk1 = new CheckBox(“checkbox1”,

new PropertyModel(this, “checkbox1”));

final CheckBox chk2 = new CheckBox(“checkbox2”,

new PropertyModel(this, “checkbox2”));

Q7. How To Create 404 Error Page?







public class WicketApplication extends WebApplication {


protected void init() {

  mount(new QueryStringUrlCodingStrategy(“error404”,ErrorPage404.class));



Q8. What Is Pallet Component In Apache-wicket?

Wicket extension comes with a special “Palette” component, which render two select boxes, and allow user to move items from one select box into another.


import org.apache.wicket.extensions.markup.html.form.palette.Palette;

 final Palette palette = new Palette(“palette”,

new ListModel(selected),

new CollectionModel(listHosting),

renderer, 10, true);


Q9. How To Create Custom Validator In Apache-wicket?

See summary steps to create a custom validator :

@Implements IValidator.

import org.apache.wicket.validation.IValidator;

 public class Strong PasswordValidator implements IValidator{


@Override validate(IValidatable validatable).

public class StrongPasswordValidator implements IValidator{


public void validate(IValidatable validatable) {

  //get input from attached component

final String field = validatable.getValue();



@Attached custom validator to form component.

public class CustomValidatorPage extends WebPage {

  public CustomValidatorPage(final PageParameters parameters) {

       final PasswordTextField password = new PasswordTextField(“password”,Model.of(“”));

//attached custom validator to password field

password.add(new StrongPasswordValidator());




Q10. How To Create Select Option As Menu Wise In Apache-wicket?


import org.apache.wicket.extensions.markup.html.form.select.Select;

import org.apache.wicket.extensions.markup.html.form.select.SelectOption;

        //variable to hold the selected value from dropdown box,

        //and also make “jQuery” selected by default

        private String selected = “jQuery”;

  Select languages = new Select(“languages”, new PropertyModel(this, “selected”));


languages.add(new SelectOption(“framework1”, new Model(“Wicket”)));

languages.add(new SelectOption(“framework2”, new Model(“Spring MVC”)));

languages.add(new SelectOption(“framework3”, new Model(“JSF 2.0”)));

languages.add(new SelectOption(“Script1”, new Model(“jQuery”)));

languages.add(new SelectOption(“Script2”, new Model(“prototype”)));

 //HTML for dropdown box

Q11. How To Create A Textarea In Apache-wicket?

//create a textarea field for address

final TextArea address = new TextArea(“address”,Model.of(“”));


Q12. What Is About Web Application In Wicket?

A web application is a subclass of Application which associates with an instance of WicketServlet to serve pages over the HTTP protocol. This class is intended to be subclassed by framework clients to define a web application.

Q13. How To Create Fileupload Field In Apache-wicket?


import org.apache.wicket.markup.html.form.upload.FileUploadField;


form.add(fileUpload = new FileUploadField(“fileUpload”));


Q14. What Are Wicket Models?

A Model holds a value for a component to display and/or edit :

  • Simple Models
  • Dynamic Models
  • Property Models
  • Compound Property Models
  • Wrapped Object Models
  • Resource Models
  • Detachable Models
  • Chaining models

Q15. How To Create A Password Field In Apache-wicket?

create a password field

final PasswordTextField password = new PasswordTextField(“password”, Model.of(“”));

//for properties file


Q16. What Is Wicket Framework?

  • Wicket is one of the most recent in a long line of Java web development frameworks.Wicket is a component-basedframework, which puts it in stark contrast to some of the earlier solutions to the sometimes monotonous task of web programming.Wicket builds on top of Sun’s servlet API. Wicket is mostly removed from the request/response nature that is inherent with the web and Servlets. Instead of building controllers that must service many users and threads simultaneously, taking in requests, returning responses, and never storing any state, the Wicket developer thinks in terms of stateful components. Instead of creating a controller or action class, he or she creates a page, places components on it, and defines how each component reacts to user input.
  • It is a lightweight component-based web application framework for the Java programming.

Q17. What Are The Ways To Create A Page In Wicket?

There are 2 ways to Create New Wicket Page.

  • create a Page Extending “WebPage” Class.
  • create a Page Extending  “BasePage” ( BasePage Should Extend “WebPage”).
  • IF you are using first Way you should Create Whole page with thier Header,Footer and other parts
  • and that HTML file’s content may be large (complicated).This is an Unreliable way to create Page. suppose you have to change some content in Header part then you have to edit all pages that having Header Content 
  • If you are using second way, first Create your BasePage then you can extend these page to other while creating new page. in that page you have to add only Body part (Content that you want to show on that Page) Using

Q18. What Is Base Class For Html Pages?

Base class for HTML pages: Webpage Class.

Q19. How To Integrate Apache-wicket With Spring?

Override Wicket application init() method with this “addComponentInstantiationListener(new SpringComponentInjector(this));“.

File : Wicket application class

package com.withoutbook;

 import org.apache.wicket.protocol.http.WebApplication;

import org.apache.wicket.spring.injection.annot.SpringComponentInjector;

import com.withoutbook.user.SimplePage;

 public class WicketApplication extends WebApplication {


public Class getHomePage() {

  return SimplePage.class; // return default page



protected void init() {


addComponentInstantiationListener(new SpringComponentInjector(this));



Now, you can inject Spring bean into Wicket component via @SpringBean.

Q20. How To Create A Textfield In Apache-wicket?

final TextField username = new TextField(“username”,Model.of(“”));


username.add(new Username  Validator());

Q21. How To Submit A Form In Apache-wicket?

Form form = new Form(“userForm”) {


protected void onSubmit() {

  final String usernameValue = username.getModelObject();

  PageParameters pageParameters = new PageParameters();

pageParameters.add(“username”, usernameValue);

setResponsePage(SuccessPage.class, pageParameters);



Q22. How To Create Single Selected Listbox?

// single list choice

private static final List FRUITS = Arrays.asList(new String[] { “Apple”, “Orange”, “Banana” });

ListChoice listFruits = new ListChoice(“fruit”, new PropertyModel(this, “selectedFruit”), FRUITS);


Q23. How To Create Multiple Selected Listbox In Apache-wicket?

//choices in list box

private static final List NUMBERS = Arrays.asList(new String[] {“Number 1”, “Number 2”, “Number 3”, “Number 4”, “Number 5”, “Number 6” });

//variable to hold the selected multiple values from listbox, 

//and make “Number 6” selected as default value

private ArrayList selectedNumber = new ArrayList(

Arrays.asList(new String[] { “Number 6” }));

 ListMultipleChoice listNumbers = new ListMultipleChoice(

“number”, new Model(selectedNumber), NUMBERS);

 //HTML for multiple select listbox

Q24. How To Create Multiple Checkboxes In Apache-wicket?

private static final List LANGUAGES = Arrays.asList(new String[] {“Java”, “.NET”, “PHP”, “Python”, “C/C++” });

// hold the checkbox values

private ArrayList languagesSelect = new ArrayList();

final CheckBoxMultipleChoice listLanguages = new CheckBoxMultipleChoice(“languages”, new Model(languagesSelect), LANGUAGES);

Q25. Dependency To Start Wicket?




Wicket need SLF4J !

You have to include the slf4j logging implementation, otherwise Wicket will be failed to start.

Wicket need resource filter

Remember to add the resource filter, Wicket puts all files in same package folder, if you didn’t define the resource filter to include everything “*” , “html”, “properties” or other resources files may failed to copy to the correct target folder.