Table of Content

• Struts Interview Questions for Freshers
• Struts Interview Questions for Intermediate
• Struts Interview Questions for Experienced

Features	Struts 1	Struts 2
Architecture	It supports monolithic architecture.	It supports modular architecture.
Configuration	The configuration is XML based configuration and file name can be any [name].xml	Configuration file name must be struts.xml
Action Handling	Action classes is not POJO actions, we need to inherit the abstract class.	Action class is POJO actions.
Tag Libraries	It has Struts custom tag library.	It has custom HTML tags and JSP Standard Tag Library (JSTL).
Request Processing	While processing the requests, it uses the concept of RequestProcessor class.	While processing requests, it uses the concept of Interceptors.

9. What is the role of the Action class in the Struts framework?

In Struts, the Action class acts as a Controller component and it is responsible for processing the requests of users. It performs the following roles:

• The Action class receives the incoming requests from users and handles those requests.
• Then it uses appropriate Model which contains all the business logic to process the requests.
• After processing the requests, the Action class provides appropriate response such as redirecting to the URL or rendering a view page.
• Then the mapping is done to the specific URLs. It ensures that the correct Action is invoked with each incoming requests.

Struts Interview Questions for Intermediate

Intermediate Struts developers can improve their skills by answering these advanced interview questions. These questions will test your knowledge and prepare you for senior-level positions, covering topics such as Struts setup, tile configuration, and custom tag libraries, as well as more complicated scenarios such as handling exceptions and constructing custom validators.

10. What is ActionForm in Struts and how it is created?

ActionForm in Struts is a JavaBean class. It acts as a container and transfers data between the presentation layer i.e. the HTML forms and the business logic layer i.e. the Action classes. It represents a collection of data from an HTML form and it provides getters and setters to get this data.

To create an ActionForm in Struts:

• Create a JavaBean Class: Develop a Java class that represents the form data. This class contains private member variables along with corresponding getter and setter methods.
• Extend ActionForm: We need to extend the org.apache.struts.action.ActionForm class in a JavaBean class to inherit the standard Struts function.
• Configure in struts-config.xml: Declare the ActionForm in struts-config.xml configuration file. Also, we need to specify its fully qualified class name.
• Use in Actions: In Action classes, specify the ActionForm as a parameter in the execute method or as a property to automatically receive and access form data.

11. What is the struts-default package?

In the Struts configuration, the struts-default package is a pre-defined default package. It contains all the default configurations and features that are commonly used in the Struts applications. This default package provides necessary frameworks and packages and by using them, we can build web applications quickly without having to configure everything from scratch.

This package typically include default configuration for interceptors, result types, and error handling, commonly used utility classes, and resources such as CSS files or JavaScript libraries. Developers can use these defaults as it is or can customize them according to the specific application requirements.

12. What is ForwardAction in Struts?

In Struts, the ForwardAction class is used to forward total control from one location to another within the Struts application like from a JSP to a local server.

• It is utilized when combining an existing application with Struts.
• Based on pre-defined configurations, it helps in directing the flow of the requests to different components.

13. How action-mapping tag is used for request forwarding in Struts configuration file?

Under action-mapping tag, forwarding options are defined in Struts configuration file i.e. struts-config.xml.

• It used to map URLs to corresponding action classes.
• For request processing, it specifies the pattern of URL with associated action class for same.

In the below example, if we click on the hyperlink, request will be forwarded to /pages/login.jsp using the below configuration from struts configuration file:

<action-mappings>
    <action path="/login" forward="/pages/welcome.jsp">
    </action>
 </action-mappings>

14. How can Validation Errors be displayed on a JSP page?

To display all Validation errors to user on JSP page based on the validation rules defined in validation.xml file, we can use Struts tags such as <html:errors> or <html:errors/> in JSP file. During form validation, these tags are used to display automatically generated error messages.

15. How duplicate form submission can be controlled in Struts?

To control duplicate form submission, we can use Token Interceptor provided by Struts.

• For each form submission, it generates a unique token using saveToken() method of action class, which is then validated upon the form submission.
• It uses isTokenValid() method to check whether the token is already used or invalid, the action will not process and it will prevent the duplicate submissions.

16. How can we access Java Beans and their properties in Struts?

To access Java Beans and their properties, we can use Bean Tag Library in Struts. This is a library which can be used to access Java beans.

17. What are the two types of Validations supported by Validator Framework in Struts?

For form data validation, Validator framework is used. The Validator framework provides two types of validation:

• Client-side Validation: This performed in user’s web browser using JavaScript before submitting the form data to the server.
• Server-side Validation: This validation is executed after the form data is submitted.

Struts Interview Questions for Experienced

In this section we have covered advanced topics such as Struts 2.x, Struts configuration with XML, and custom plugin development, these questions will push your knowledge to its limits and prepare you for leadership roles.

18. What is DynaActionForm?

DynaActionForm is a sub-class of ActionForm Class. It is used to dynamically create form beans. For form bean creation, it uses configuration files. It dynamically handles the form data without the need to create a separate form bean class for each HTML form.

19. What are ActionServlets and Why ActionServlet singleton in Struts?

In Struts, the ActionServlets are the central controller components and it manages the entire request handling process in the application. ActionServlet is singleton in Struts.

• When the request received, it routed to the corresponding Action classes based on configured mappings.
• It call to the process() method of RequestProcessor.
• It handles the overall flow of control within the application.
• ActionServlet is based on singleton design pattern because only one object needs to be created for this controller class and for each user’s request multiple threads are created later.

20. What is the role of the Struts configuration file (struts-config.xml)?

Struts Configuration file i.e. struts-config.xml only serves as a central configuration file for the Struts applications.

• It maps the incoming requests URLs with appropriate Action classes.
• Mapping is done along with the global settings such as message resources and form beans.

Refer the below sample struts-config.xml file for better understanding.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" "http://struts.apache.org/dtds/struts-config_1_3.dtd">

<struts-config>
    <!-- Define action mappings -->
    <action-mappings>
        <!-- Define mappings between URLs and action classes -->
    </action-mappings>
    
    <!-- Define global settings such as form beans and message resources -->
</struts-config>

21. What is meant by the validate() and reset() function in Struts?

• validate(): This function is used to perform server-side validation of form inputs based on the validation rules defined in the ActionForm class.
• reset(): This function determines whether to reset or delete form fields to their default values.

22. What are the condition for actionForm to work correctly?

ActionForm should follow the following conditions to work correctly.

• ActionForm must have a no argument constructor.
• For all properties, it should have public getter and setter methods.
• It needs to extend the org.apache.struts.action.ActionForm class or it can implement the org.apache.struts.action.ActionForm interface.
• It must be declared in the struts-config.xml file with a unique name and linked to the corresponding Action mapping.

23. What are OGNL and ValueStack in Struts?

OGNL stands for Object Graph Navigation Language. It is an expression language of Struts2. ValueStack is a stack and it contains all values and action specific object with data linked to actions. The values or data of ValueStack are changed through OGNL library.

For more details please refer to this article: Struts 2 OGNL

24. How Client side validation is enables on a JSP form?

To enable client-side validation in Struts, we need to enable the validator plug-in inside the struts configuration file i.e. struts-config.xml. By adding the below configurations in struts-config.xml file, this process can be done.

<plug-in className="org.apache.struts.validator.ValidatorPlugIn">
<set-property
property="pathname"
value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
</plug-in>

Now, the validation rules are defined in validation.xml file. Let’s see a simple example, if a form contains email field, and we want to do client side validation on email field, following code will be added in validation.xml file:

<form name="gfgForm">
<field property="email"
depends="required">
<arg key="gfgForm.email"/>

25. What is declarative exception handling in Struts?

• In Struts, when the logic for exception handling has defined within the action tag or in struts-config.xml file, it is known as declarative exception handling.
• For this, we can specify how to handle specific exceptions thrown by actions like redirecting to different actions or displaying custom error pages etc. in struts configuration file.

Conclusion

In this free interview preparation guide, we have covered a wide range of Struts interview questions and answers to help you excel in your next interview. From basic concepts to advanced topics, these questions have been carefully selected to assess your knowledge and understanding of the Struts framework.