Struts Interview Questions and Answers

Answer - 41 : - Yes. The issue is that only one action class can be associated with a single form. So the real issue is how do I decode multiple submit types to a single Action class. There is more than one way to achieve this functionality. The way that is suggested by struts is right out of the javadoc for LookupDispatchAction . Basically, LookupDispatchAction is using the keys from ApplicationProperties.resources as keys to a map of actions available to your Action class. It uses reflection to decode the request and invoke the proper action. It also takes advantage of the struts tags and is straight forward to implement. You can roll your own with JavaScript events and javascript:void (document.forms["myform"].submit) on any html element. This gives you control of how you want your page to look. Again you will have to decode the expected action in the execute method of your action form if you choose this route.

Answer - 42 : - A problem with a checkbox is that the browser will only include it in the request when it is checked. If it is not checked, the HTML specification suggests that it not be sent (i.e. omitted from the request). If the value of the checkbox is being persisted, either in a session bean or in the model, a checked box can never unchecked by a HTML form -- because the form can never send a signal to uncheck the box. The application must somehow ascertain that since the element was not sent that the corresponding value is unchecked. The recommended approach for Struts applications is to use the reset method in the ActionForm to set all properties represented by checkboxes to null or false. The checked boxes submitted by the form will then set those properties to true. The omitted properties will remain false. Another solution is to use radio buttons instead, which always submit a value. It is important to note that the HTML specification recommends this same behavior whenever a control is not "successful". Any blank element in a HTML form is not guaranteed to submitted. It is therefor very important to set the default values for an ActionForm correctly, and to implement the reset method when the ActionForm might kept in session scope.

Answer - 43 : - Struts is designed to encourage a Model 2/MVC architecture. But there is nothing that prevents you from using Model 1 techniques in your JavaServer Pages, so the answer to the question is "Yes, you can". Though, using Model 1 techniques in a Struts application does go against the grain. The approach recommended by most Struts developers is to create and populate whatever objects the view may need in the Action, and then forward these through the request. Some objects may also be created and stored in the session or context, depending on how they are used. Likewise, there is nothing to prevent you from using scriptlets along with JSP tags in your pages. Though, many Struts developers report writing very complex scriplet-free applications and recommend the JSP tag approach to others. For help with Model 1 techniques and scriptlets, you might consider joining the Javasoft JSP-interest mailing list, where there are more people still using these approaches.

Answer - 44 : - You can submit a form with a link as below. BTW, the examples below assume you are in an block and 'myForm' is picked up from the struts-config.xml name field of the action. ... the java part ... class MyAction extends ActionForm implements Serializable { public ActionForward execute (ActionMapping map, ActionForm form, HttpServletRequest req, HttpServletResponse) { String myAction = req.getParameter("myAction"); if (myAction.equals("save") { // ... save action ... } else if (myAction.equals("delete") { // ... delete action ... } } } } This is just one of many ways to achieve submitting a form and decoding the intended action. Once you get used to the framework you will find other ways that make more sense for your coding style and requirements. Just remember this example is completely non-functional without JavaScript.

Answer - 45 : - Yes. There are several ways that you can use other beans or hashmaps with ActionForms. * ActionForms can have other beansor hashmaps as properties * "Value Beans" or "Data Transfer Objects" (DTOs) can be used independently of ActionForms to transfer data to the view * ActionForms can use Maps to support "dynamic" properties (since Struts 1.1) ActionForms (a.k.a. "form beans") are really just Java beans (with a few special methods) that Struts creates and puts into session or request scope for you. There is nothing preventing you from using other beans, or including them in your form beans. Here are some examples: Collections as properties Suppose that you need to display a pulldown list of available colors on an input form in your application. You can include a string-valued colorSelected property in your ActionForm to represent the user's selection and a colorOptions property implemented as a Collection (of strings) to store the available color choices. Assuming that you have defined the getters and setters for the colorSelected and colorOptions properties in your orderEntryForm form bean, you can render the pulldown list using: The list will be populated using the strings in the colorOptions collection of the orderEntryForm and the value that the user selects will go into the colorSelected property that gets posted to the subsequent Action. Note that we are assuming here that the colorOptions property of the orderEntryForm has already been set. See How can I prepopulate a form? for instructions on how to set form bean properties before rendering edit forms that expect properties to be pre-set. Independent DTO An Action that retrieves a list of open orders (as an ArrayList of Order objects) can use a DTO independently of any form bean to transfer search results to the view. First, the Action's execute method performs the search and puts the DTO into the request: ArrayList results = businessObject.executeSearch(searchParameters); request.setAttribute("searchResults",results); Then the view can iterate through the results using the "searchResults" request key to reference the DTO: ` ... ... ... <-- Edit user registration --> ... <-- Save user registration --> ... Note the following features of this approach: * Both the /editRegistration and /saveRegistration actions use the same form bean. * When the /editRegistration action is entered, Struts will have pre-created an empty form bean instance, and passed it to the execute() method. The setup action is free to preconfigure the values that will be displayed when the form is rendered, simply by setting the corresponding form bean properties. * When the setup action completes configuring the properties of the form bean, it should return an ActionForm that points at the page which will display this form. If you are using the Struts JSP tag library, the action attribute on your tag will be set to /saveRegistration in order for the form to be submitted to the processing action. * Note that the setup action (/editRegistration) turns off validation on the form that is being set up. You will normally want to include this attribute in the configuration

Answer - 49 : - Struts is mainly a server-side technology. We bundled in some JSP tags to expose the framework components to your presentation page, but past that, the usual development process applies. Interactive pages require the use of JavaScript. (That's why it was invented.) If you want things popping up or doing this when they click that, you are outside the scope of Struts and back into the web development mainstream. You use JavaScript with Struts the same way you use with any presentation page. Since JavaScript is a client-side technology, you can use simple relative references to your scripts. If you need to fire a JavaScript from a HTML control, the Struts HTML tags have properties for the JavaScript events

Answer - 50 : - Yes. If your Action does not need any data and it does not need to make any data available to the view or controller component that it forwards to, it doesn't need a form. A good example of an Action with no ActionForm is the LogoffAction in the struts example application: This action needs no data other than the user's session, which it can get from the Request, and it doesn't need to prepare any view elements for display, so it does not need a form. However, you cannot use the tag without an ActionForm. Even if you want to use the tag with a simple Action that does not require input, the tag will expect you to use some type of ActionForm, even if it is an empty subclass without any properties.