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Struts Interview Questions and Answers

Ques 31. Why are some of the class and element names counter-intuitive?

The framework grew in the telling and, as it evolved, some of the names drifted.
The good thing about a nightly build, is that everything becomes available to the community as soon as it is written. The bad thing about a nightly build is that things like class names get locked down early and then become difficult to change.

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Ques 32. Why is ActionForm a base class rather than an interface?

The MVC design pattern is very simple to understand but much more difficult to live with. You just need this little bit of Business Logic in the View logic or you need just that little bit of View logic in the Business tier and pretty soon you have a real mess.
Making ActionForm a class takes advantage of the single inheritance restriction of Java to it makes it more difficult for people to do things that they should not do.
ActionForms implemented as interfaces encourage making the property types match the underlying business tier instead of Strings, which violates one of the primary purposes for ActionForms in the first place (the ability to reproduce invalid input, which is a fundamental user expectation). ActionForms as an interface would also encourage using existing DAO objects as ActionForms by adding 'implements ActionForm' to the class. This violates the MVC design pattern goal of separation of the view and business logic.
Since the goal of struts is to enforce this separation, it just makes more sense for Struts to own the ActionForm.
DynaActionForms relieve developers of maintaining simple ActionForms. For near zero maintenance, try Niall Pemberton's LazyActionForm

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Ques 33. Do ActionForms have to be true JavaBeans?

The utilities that Struts uses (Commons-BeanUtils since 1.1) require that ActionForm properties follow the JavaBean patterns for mutators and accessors (get*,set*,is*). Since Struts uses the Introspection API with the ActionForms, some containers may require that all the JavaBean patterns be followed, including declaring "implements Serializable" for each subclass. The safest thing is to review the JavaBean specification and follow all the prescribed patterns.
Since Struts 1.1, you can also use DynaActionForms and mapped-backed forms, which are not true JavaBeans. For more see ActionForm classes in the User Guide and Using Hashmaps with ActionForms in this FAQ.

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Ques 34. Can I use multiple HTML form elements with the same name?

Yes. Define the element as an array and Struts will autopopulate it like any other.
private String[] id= {};
public String[] getId() { return this.id; }
public void setItem(String id[]) {this.id = id;}
And so forth

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Ques 35. Why doesn't the focus feature on the <html:form> tag work in every circumstance?

Unfortunately, there is some disagreement between the various browsers, and different versions of the same browser, as to how the focus can be set. The <html:form> tag provides a quick and easy JavaScript that will set the focus on a form for most versions of most browsers. If this feature doesn't work for you, then you should set the focus using your own JavaScript. The focus feature is a convenient "value-add" -- not a core requirement of the tag. If you do come up with a JavaScript that provides the final solution to this project, please post your patch to this Bugzilla ticket.

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