Struts Interview Questions and Answers

Answer - 51 : - The Struts tags seem to provide only the most rudimentary functionality. Why is there not better support for date formatting and advanced string handling? Three reasons: First, work started on the JSTL and we didn't want to duplicate the effort. Second, work started on Java Server Faces, and we didn't want to duplicate that effort either. Third, in a Model 2 application, most of the formatting can be handled in the ActionForms (or in the business tier), so all the tag has to do is spit out a string. This leads to better reuse since the same "how to format" code does not need to be repeated in every instance. You can "say it once" in a JavaBean and be done with it. Why don't the Struts taglibs offer more layout options? Since the Struts tags are open source, you can extend them to provide whatever additional formatting you may need. If you are interested in a pre-written taglib that offers more layout options, see the struts-layout taglib. In the same arena, there is a well regarded contributor taglib that can help you create Menus for your Struts applications.

Answer - 52 : - The tag is not intended for use with client-side references like those used to launch Javascripts or email clients. The purpose of link tag is to interject the context (or module) path into the URI so that your server-side links are not dependent on your context (or module) name. It also encodes the link, as needed, to maintain the client's session on the server. Neither feature applies to client-side links, so there is no reason to use the tag. Simply markup the client-side links using the standard tag.

Answer - 53 : - Attribute minimization (that is, specifying an attribute with no value) is a place where HTML violates standard XML syntax rules. This matters a lot for people writing to browsers that support XHTML, where doing so makes the page invalid. It's much better for Struts to use the expanded syntax, which works the same on existing browsers interpreting HTML, and newer browsers that expect XHTML-compliant syntax. Struts is following the behavior recommended by the XHTML specification

Answer - 54 : - The short answer to this question is: No, you are not limited to JavaServer Pages. The longer answer is that you can use any type of presentation technology which can be returned by a web server or Java container. The list includes but is not limited to: * JavaServer Pages, * HTML pages, * WML files, * Java servlets, * Velocity templates, and * XML/XLST Some people even mix and match apparently unrelated technologies, like PHP, into the same web application.

Answer - 55 : - First off, there's an even newer Validator rule called validwhen, which is almost certainly what you want to use, since it is much easier and more powerful. It will be available in the first release after 1.1 ships. The example shown below could be coded with validwhen as: test ((((sex == 'm') OR (sex == 'M')) AND (*this* == null)) OR (*this* != null)) Let's assume you have a medical information form with three fields, sex, pregnancyTest, and testResult. If sex is 'f' or 'F', pregnancyTest is required. If pregnancyTest is not blank, testResult is required. The entry in your validation.xml file would look like this: field[0] sex fieldTest[0] EQUAL fieldValue[0] F field[1] sex fieldTest[1] EQUAL fieldValue[1] f fieldJoin OR tag allows you to dump all errors on your page or a particular error associated with a particular property. The input attribute of the struts-config.xml action allows you to send validation errors to a particular jsp / html / tile page. 4) You can have the system perform low level validations and client side feedback using a ValidatorForm or its derivatives. This will generate javascript and give instant feedback to the user for simple data entry errors. You code your validations in the validator-rules.xml file. A working knowledge of regular expressions is necessary to use this feature effectively.

Answer - 57 : - ActionForms are added to a servlet scope (session or request) as beans. What this means is that, for certain functionality to be available, your ActionForms will have to follow a few simple rules. First, your ActionForm bean must have a zero-arguments constructor. This is required because Struts must be able to dynamically create new instances of your form bean class, while knowing only the class name. This is not an onerous restriction, however, because Struts will also populate your form bean's properties (from the request parameters) for you. Second, the fields of your form bean are made available to the framework by supplying public getter and setter methods that follow the naming design patterns described in the JavaBeans Specification. For most users, that means using the following idiom for each of your form bean's properties: private {type} fieldName; public {type} getFieldName() { return (this.fieldName); } public void setFieldName({type} fieldName) { this.fieldName = fieldName; } NOTE - you MUST obey the capitalization conventions shown above for your ActionForm properties to be recognized. The property name in this example is "fieldName", and that must also be the name of the input field that corresponds to this property. A bean property may have a "getter" method and a "setter" method (in a form bean, it is typical to have both) whose name starts with "get" or "set", followed by the property name with the first character capitalized. (For boolean properties, it is also legal to use "is" instead of "get" as the prefix for the getter method.) Advanced JavaBeans users will know that you can tell the system you want to use different names for the getter and setter methods, by using a java.beans.BeanInfo class associated with your form bean. Normally, however, it is much more convenient to follow the standard conventions. WARNING - developers might be tempted to use one of the following techniques, but any of them will cause your property not to be recognized by the JavaBeans introspection facilities, and therefore cause your applications to misbehave: * Using getter and setter method names that do not match - if you have a getFoo() method for your getter, but a setBar() method for your setter, Java will not recognize these methods as r

Answer - 58 : - The simplest way is to have two actions. The first one has the job of setting the form data, i.e. a blank registration screen. The second action in our writes the registration data to the database. Struts would take care of invoking the validation and returning the user to the correct screen if validation was not complete. The EditRegistration action in the struts example application illustrates this: < action path="/editRegistration"> type="org.apache.struts.webapp.example.EditRegistrationAction" attribute="registrationForm" scope="request" validate="false"> When the /editRegistration action is invoked, a registrationForm is created and added to the request, but its validate method is not called. The default value of the validate attribute is true, so if you do not want an action to trigger form validation, you need to remember to add this attribute and set it to false.

Answer - 59 : - The basic idea is a series of actions with next, back, cancel and finish actions with a common bean. Using a LookupDispatchAction is reccomended as it fits the design pattern well and can be internationalized easily. Since the bean is shared, each choice made will add data to the wizards base of information. A sample of struts-config.xml follows: < form-beans> Question - 60 : - What's the best way to deal with migrating a large application from Struts to JSF? Is there any tool support that can help?

Answer - 60 : - Answer: This is a complicated task depending on your Struts application. Because the two frameworks have different goals, there are some challenges. Migrate your response pages first. Keep the Struts controller and place and forward to JSF pages. Then you can configure Struts forwards to go through the Faces servlet. Consider looking at the Struts-Faces framework from Apache. See the framework chapter in JSF in Action.