Top 30 Struts Interview Questions and Answers (2026)
James Hartman
Preparing for a Struts interview? Time to consider which challenges may appear. Understanding Struts Interview helps candidates anticipate expectations and showcase insight through questions that reveal depth and value effectively.
Struts continues to offer strong career opportunities as companies modernize Java applications, demanding technical experience and domain expertise for scalable solutions. Working in the field sharpens analyzing skills and technical expertise that team leaders and seniors expect, helping freshers, mid-level, and experienced professionals crack common and advanced questions for growth. Read more…
👉 Free PDF Download: Struts Interview Questions & Answers
Top Struts Interview Questions and Answers
1) How would you explain the core architecture of the Struts framework and its lifecycle in a real-world Java web application?
The Struts architecture follows the Model–View–Controller (MVC) pattern, where each layer has a clearly defined responsibility that promotes separation of concerns. The lifecycle begins when a client sends a request, which is intercepted by the ActionServlet. This servlet consults the struts-config.xml to determine which Action class must process the request. The Action class interacts with the Model layer (business logic or services), prepares an ActionForward, and directs the flow to an appropriate JSP page for rendering.
Example: In an e-commerce checkout flow, the Action class validates the cart, interacts with payment services, and forwards the result to success or error JSPs.
Struts Lifecycle Overview
| Step | Description |
|---|---|
| 1 | Client request reaches ActionServlet |
| 2 | Servlet reads configuration to locate Action class |
| 3 | Action class executes business logic |
| 4 | Return ActionForward |
| 5 | JSP renders final response |
2) What different types of Action classes exist in Struts, and what factors determine when each should be used?
Struts provides several Action class types to handle diverse requirements, allowing developers to choose the most suitable implementation for specific use cases. A standard Action processes simple requests, while specialized actions such as DispatchAction or LookupDispatchAction enable method-level routing and improved modularity. The choice depends on factors such as the number of operations, need for reusability, or the need to minimize configuration.
Example: If a page contains multiple operations—such as add, edit, and delete—DispatchAction avoids creating multiple individual Action classes.
| Action Type | Characteristics | Use Case |
|---|---|---|
| Action | Basic request handling | Simple request–response flows |
| DispatchAction | Maps multiple methods | CRUD operations on a single page |
| LookupDispatchAction | Uses key–method mapping | Multi-language UIs |
| MappingDispatchAction | Uses action mapping | Dynamic method selection |
3) Explain the difference between Struts 1 and Struts 2 and highlight the advantages and disadvantages of upgrading.
Struts 1 and Struts 2 differ fundamentally in architecture, request handling, and extensibility. Struts 1 relies heavily on servlet APIs, while Struts 2 is built on top of WebWork and leverages interceptors, OGNL, and POJO-based actions. Upgrading brings improved flexibility and modern features, but migration also introduces complexity due to configuration changes and deprecated components.
Advantages and Disadvantages
| Aspect | Struts 1 | Struts 2 |
|---|---|---|
| Action Classes | Must extend framework class | Simple POJOs |
| Data Handling | Uses ActionForm |
Uses normal JavaBeans |
| Extensibility | Limited | Highly customizable interceptors |
| Migration Impact | No change | Requires code refactoring |
Summary: Upgrading offers performance improvements and reduced boilerplate, but demands substantial rework of existing applications.
4) Which components make up the Struts configuration system, and how do they work together to manage the application flow?
Struts configuration is centered on struts-config.xml, which instructs the framework on how to map requests, manage forms, wire Action classes, and determine the rendering views. This configuration file includes form-beans, action-mappings, global-forwards, plug-ins, and message-resources. Together, these components unify application flow in a consistent manner.
Example: A login form uses a form bean for data binding, an action mapping for routing, and message resources for validation messages.
Their combined structure ensures predictable request routing and streamlined maintainability.
5) What role do Interceptors play in Struts 2, and can you discuss their lifecycle with examples?
Interceptors in Struts 2 function as modular processing units that execute before and after an Action method. They enable cross-cutting functionalities such as validation, logging, profiling, and authentication. The lifecycle begins when a request enters the framework, runs through a stack of interceptors, triggers the Action method, and then passes control back through the same interceptors for post-processing.
Example: The params interceptor populates Action properties, while the validation interceptor ensures input correctness before execution.
Interceptors reduce boilerplate code and improve modularity by applying logic consistently across actions.
6) When working with Struts validation, how do you describe the different ways to implement validation rules, and what are the benefits of each?
Struts supports two primary validation approaches: Declarative Validation using validation.xml and Programmatic Validation inside Action or form classes. Declarative validation offers centralized rule management and simplified maintenance, while programmatic validation is useful when validations require dynamic, context-specific rules.
Example: Declarative validation ensures that an email field is always checked, while programmatic validation might enforce unique username checks via database calls.
| Validation Type | Advantages | Disadvantages |
|---|---|---|
| Declarative | Centralized, reusable, easy to maintain | Less flexible for dynamic rules |
| Programmatic | Highly customizable | Increases class complexity |
7) How do you differentiate ActionForm from POJO-based forms in Struts, and why does Struts 2 eliminate ActionForm completely?
Struts 1 uses ActionForm objects to encapsulate request data, requiring developers to maintain separate form beans that often duplicate domain models. In contrast, Struts 2 allows direct use of POJOs with automatic parameter binding via OGNL, reducing redundancy and improving clarity.
Struts 2 removes ActionForm to promote cleaner design, reduced boilerplate, and easier testing.
Example: A User POJO can simultaneously represent form data and domain representation in Struts 2, whereas Struts 1 requires separate UserForm.
8) What are the different types of result types in Struts 2, and how are they used within an application?
A result type dictates how the outcome of an Action is rendered. Struts 2 supports a range of result types, including dispatcher, redirect, redirectAction, chain, stream, and custom types. Each serves a unique purpose depending on navigation patterns and interaction needs.
Example: File download modules rely on the stream result type, while page transitions often use dispatcher.
| Result Type | Purpose |
|---|---|
| Dispatcher | Forward to JSP |
| Redirect | New request cycle |
| RedirectAction | Redirect to another action |
| Chain | Invoke another action directly |
| Stream | Binary output (files, reports) |
9) Can you describe the DispatcherServlet or ActionServlet role in Struts and why it is essential for request processing?
The ActionServlet (Struts 1) or filter-based dispatcher (Struts 2) acts as the central controller that manages every request entering the framework. It interprets configuration files, selects the correct Action class, manages lifecycle elements, invokes business logic, and determines which view should be rendered. Without this centralized mechanism, Struts would lack predictable routing and could not enforce consistent MVC separation.
Example: In a banking portal, the dispatcher ensures that account summary requests reach the correct Action and that validation errors return the user to the same form with messages intact.
10) Explain how internationalization (i18n) works in Struts and what characteristics make the framework suitable for multi-language applications.
Internationalization in Struts is achieved through property files defined as message resources. These files hold key–value pairs for different languages. The framework automatically selects the appropriate resource bundle based on user locale. Struts provides tag libraries such as <bean:message> (Struts 1) and <s:text> (Struts 2) to render translated content dynamically.
Characteristics that make Struts strong in i18n include structured resource management, automatic locale detection, and reusable message keys.
Example: A login page can display “Username” in English and “Nombre de usuario” in Spanish by switching locale settings.
11) What mechanisms does Struts provide for exception handling, and how do different approaches impact application stability?
Struts supports both declarative and programmatic exception handling, allowing developers to centralize or customize error responses. Declarative handling uses the <exception> tag inside struts-config.xml or Struts 2’s global exception mappings, providing a clean separation between business logic and error responses. Programmatic handling places try–catch blocks within Action classes for finer control. Declarative exception handling improves consistency and maintainability, while programmatic handling allows highly contextual responses. For example, authentication errors may be routed to a warning page, whereas system-level failures may forward users to a maintenance screen. Together, these mechanisms enhance stability by preventing error leakage and delivering user-friendly responses.
12) How does the Struts tag library simplify JSP development, and what types of tags are most commonly used?
The Struts tag library abstracts repetitive JSP tasks by offering custom tags that interact seamlessly with the framework. These tags handle form creation, iteration, message retrieval, conditional rendering, and dynamic content binding without requiring extensive Java code inside JSPs. In Struts 1, tags such as <html:form>, <bean:write>, and <logic:iterate> are frequently used, while Struts 2 integrates UI tags like <s:form>, <s:textfield>, and <s:iterator>.
Example: A developer can bind form fields directly to ActionForm properties using <html:text property="username"/>, reducing the chance of errors and improving maintainability.
13) Where does the OGNL (Object Graph Navigation Language) engine fit into Struts 2, and what benefits does it provide?
OGNL is the expression language powering Struts 2, responsible for evaluating expressions, binding request parameters to POJOs, and enabling dynamic property access. It allows developers to navigate nested object graphs easily, improving flexibility and reducing boilerplate code. One primary benefit is its ability to map form data directly into complex domain objects without additional parsing logic.
Example: A nested address object inside a Customer class can be populated with a single form submission using fields such as address.street or address.city, demonstrating OGNL’s deep graph navigation capabilities.
14) What is the difference between RequestProcessor in Struts 1 and the Interceptor Stack in Struts 2?
The RequestProcessor in Struts 1 acts as a monolithic controller that manages request preprocessing, validation, and dispatching. It is rigid and difficult to extend, often requiring subclassing to customize behavior. In contrast, Struts 2 uses an Interceptor Stack, a chain of pluggable components that run around Action execution. This model is highly modular and allows developers to insert, remove, or reorder interceptors to adjust application behavior.
Comparison Table
| Feature | RequestProcessor (Struts 1) | Interceptor Stack (Struts 2) |
|---|---|---|
| Extensibility | Limited | Highly flexible |
| Customization | Requires subclassing | Configurable XML-based |
| Behavior | Centralized | Distributed and modular |
| Benefits | Simplicity | Better separation of concerns |
15) Can you explain how Struts supports file upload and what factors developers should consider when implementing this feature?
Struts simplifies file upload using Apache Commons FileUpload API in Struts 1 and built-in <s:file> tag handling in Struts 2. The framework parses multipart requests, binds uploaded file objects to form beans or POJOs, and allocates temporary storage. Developers must consider key factors such as file size limits, MIME-type validation, storage location, and potential security risks such as malicious file uploads.
Example: In an HR portal, upload functionality for resumes should enforce size restrictions, validate PDF or DOCX types, and store files in secure directories to prevent unauthorized access.
16) Which features make Struts 2 more flexible than Struts 1 in terms of extending framework behavior?
Struts 2’s flexibility comes from its interceptor-based architecture, POJO actions, dependency injection support, and the ability to create custom result types. These features allow developers to adapt the framework organically to evolving business needs without altering its core structure. In contrast, Struts 1’s servlet-dependent architecture limits extension capabilities.
Example: Logging, profiling, and security checks can be implemented as interceptors and applied globally, eliminating code duplication. The use of plugins further enhances extensibility by modularizing additional features such as Spring integration or JSON output generation.
17) What characteristics differentiate Struts from Spring MVC, and when should one framework be preferred over the other?
Struts emphasizes action-based MVC and a strong configuration-driven approach, while Spring MVC offers annotation-driven controllers, lighter configuration, and deep integration with the Spring ecosystem. Struts is suitable for legacy enterprise applications requiring structured XML-based flows, whereas Spring MVC provides greater flexibility, dependency injection, and modern REST support.
Differences Between Struts and Spring MVC
| Aspect | Struts | Spring MVC |
|---|---|---|
| Controller Type | Action-based | Annotation-based |
| Config Style | XML-heavy | Lightweight |
| Testing | Moderately easy | Very easy |
| Integration | Limited | Extensive Spring ecosystem |
| Benefits | Mature and stable | Modern, modular, scalable |
Spring MVC is preferred for new projects, while Struts remains viable for maintaining existing applications.
18) How do you configure and use Tiles with Struts, and what advantages does it bring to UI development?
Tiles is a templating framework that integrates with Struts to allow reusable page layouts. Configuration involves defining layout templates in tiles-defs.xml, mapping attributes such as headers, footers, and body sections, and then linking action outcomes to specific tile definitions. Tiles promotes consistent appearance, reduces duplication, and simplifies UI updates.
Example: A dashboard page can reuse the same navigation bar and footer definitions while changing only the content area, resulting in faster development and more maintainable codebases.
19) Do Struts applications support dependency injection, and how can DI frameworks be integrated for better modularity?
Struts 1 does not natively support dependency injection, but Struts 2 allows seamless integration with DI frameworks such as Spring. Through plugins like struts2-spring-plugin, Action classes can receive dependencies automatically, reducing coupling and improving testability.
Example: An OrderAction class can have its OrderService injected directly rather than manually instantiating it, resulting in cleaner architecture and easier unit testing. Dependency injection brings benefits such as configurability, modularity, and easier swapping of implementations.
20) What steps are involved in migrating an existing Struts 1 application to Struts 2, and what are the common challenges?
Migrating from Struts 1 to Struts 2 requires reworking Action classes, replacing ActionForms with POJO models, redesigning validation rules, updating configuration files, and modifying JSP tags. Developers must also adapt to OGNL and interceptor-based processing. Common challenges include handling deprecated features, refactoring custom RequestProcessor logic, and adjusting form binding logic.
Example: A legacy banking application may require replacing dozens of ActionForms with simple domain objects while ensuring backward compatibility. Despite these challenges, the migration yields long-term benefits such as cleaner architecture, enhanced extensibility, and reduced maintenance overhead.
21) What types of configuration files are used in Struts 1 and Struts 2, and how does their structure influence application maintainability?
Struts 1 primarily relies on struts-config.xml, which contains action mappings, form-bean definitions, global forwards, and message-resources. This single large file often grows complex as the application scales, making maintainability harder. Struts 2 improves this by splitting configuration across multiple struts.xml files, packages, and optional annotation-based configurations. Developers can organize modules logically, reducing coupling and enhancing clarity.
Example: A large ERP system can divide its configuration into modules like inventory-struts.xml and finance-struts.xml, resulting in better readability and easier lifecycle management.
22) How does the Struts Validator Framework work, and what benefits does it bring compared to manual validation?
The Struts Validator Framework automates input validation using XML-defined rules, JavaScript generation, and built-in validation types such as required fields, email patterns, and length constraints. It reduces boilerplate code, ensures consistency, and supports both client-side and server-side validation simultaneously. Manual validation, by contrast, requires repetitive coding and increases the risk of inconsistent business rules.
Example: A registration form can enforce email format checks and mandatory fields using declarative XML rules without adding Java code. This dual-layer validation improves reliability and reduces user errors.
23) What are the characteristics of the ValueStack in Struts 2, and how does it influence data availability in Views?
The ValueStack is a core component that stores application data during a request lifecycle. It holds Action properties, temporary context values, and OGNL-accessible objects. Its layered structure ensures that JSP tags and OGNL expressions retrieve the correct values automatically. The ValueStack improves accessibility by exposing data without requiring explicit getters or scope references.
Example: When a ProductAction loads a product list, the ValueStack allows <s:iterator value="products"> to retrieve the list directly, simplifying UI development and reducing coupling between view and controller layers.
24) What difference exists between session management in Struts and standard servlet APIs, and how can Struts improve session handling?
Struts builds on standard servlet APIs but introduces helper mechanisms such as session-scoped ActionForms (Struts 1) and session-aware interfaces in Struts 2 (like SessionAware). These abstractions simplify common tasks, such as storing user details or maintaining shopping carts, by hiding raw HttpSession complexity. Struts also enables type-safe access to session objects and reduces boilerplate code.
Example: A shopping cart can be stored in session without manually retrieving HttpSession in each action; Struts 2 injects the session map automatically through the interceptor lifecycle.
25) How do Interceptor Stacks in Struts 2 provide different ways to manage cross-cutting concerns across modules?
Interceptor Stacks are configurable collections of interceptors that apply to specific packages or actions. They centralize cross-cutting concerns such as logging, authentication, validation, file upload, and parameter binding. Developers can define custom stacks to fine-tune application behavior for different modules.
Example: A financial transaction module might require a stricter interceptor stack including audit logging, authentication, and encryption checks, while a public catalog module may use a lighter stack. This flexibility enhances maintainability and modular design.
26) What are ActionErrors and ActionMessages in Struts 1, and how do they enhance user-facing validation feedback?
ActionErrors and ActionMessages encapsulate error and success messages generated during Action execution. They allow developers to collect multiple messages and display them collectively in JSPs using tags like <html:errors> or <html:messages>. This provides clean separation between logic and presentation.
Example: A login attempt may generate an ActionError for incorrect credentials and an ActionMessage for password reset availability. By aggregating them, users receive detailed and structured feedback without exposing internal implementation details.
27) How do you configure multiple modules in a Struts application, and what advantages does this modular approach offer?
Struts 1 supports multi-module applications through separate configuration files, each mapped to unique URL prefixes. This enables teams to maintain isolated functional areas—such as admin, user, and reporting modules—with independent lifecycle flows. Struts 2 also promotes modularity using packages.
Benefits:
- Better separation of concerns
- Parallel development by distributed teams
- Reduced configuration conflicts
- Independent deployment and testing scopes
Example: A university portal may separate student, faculty, and admin modules to simplify development and maintenance.
28) When should you use DispatchAction or its variations, and what difference between these classes helps in code optimization?
DispatchAction allows mapping multiple operations within a single Action class by selecting a method based on a request parameter. This reduces the number of Action classes and centralizes related logic. Variations include LookupDispatchAction, which maps method names to resource keys for internationalization, and MappingDispatchAction, which leverages action mapping details.
Difference Summary
| Class | Behavior | Best Use |
|---|---|---|
| DispatchAction | Uses parameter to choose method | CRUD operations |
| LookupDispatchAction | Uses key–method map | Multi-language forms |
| MappingDispatchAction | Uses mapping to route | Complex routing logic |
This consolidation reduces redundancy and improves maintainability.
29) How do Result Types in Struts 2 enhance navigation flexibility, and what factors determine appropriate selection?
Result Types define how action outcomes transition to views or other actions. Factors that determine the selection include navigation flow, performance needs, security requirements, and content type. For instance, a redirect result avoids form resubmission issues, while a dispatcher result is faster for internal forwarding. A stream result is ideal for binary outputs such as file downloads or report generation.
Example: When generating PDF invoices, the application should use the stream result type to deliver the file directly to the browser.
30) What is the lifecycle of an Action class in Struts 2, and which steps differ significantly from Struts 1?
The Struts 2 lifecycle begins when the request hits the FilterDispatcher (or StrutsPrepareAndExecuteFilter), which initializes the ValueStack and executes the Interceptor Stack. Interceptors populate parameters, validate inputs, and prepare the Action object for invocation. After the Action executes, interceptors handle post-processing, and the framework identifies the appropriate result for rendering. Unlike Struts 1, Struts 2 uses POJO-based Actions, avoids ActionForm duplication, and processes requests through interceptors rather than a monolithic RequestProcessor.
Example: A PurchaseAction may have authentication performed by one interceptor, validation by another, and logging by a third—all without modifying the Action itself.
🔍 Top Struts Interview Questions with Real-World Scenarios and Strategic Responses
Below are 10 realistic Struts interview questions (knowledge-based, behavioral, and situational) along with strong example answers.
Each answer uses no contractions and includes the required phrases only once each across the entire list.
1) Can you explain the Struts framework and why it is used in enterprise applications?
Expected from candidate: Demonstrate understanding of MVC architecture, separation of concerns, and enterprise benefits.
Example Answer: “Struts is a Java-based web application framework that follows the Model-View-Controller architecture. It is used in enterprise applications because it provides centralized configuration, reusable components, and a clear separation of concerns. These features help teams maintain large-scale applications more efficiently.”
2) How does the MVC architecture work within Struts?
Expected from candidate: Discuss roles of ActionServlet, Action classes, and JSP views.
Example Answer: “In Struts, the controller is managed by the ActionServlet, which receives user requests and routes them to the appropriate Action class. The model contains the business logic and data handling, while the view uses JSPs to present the processed information. This structure improves maintainability and reduces coupling.”
3) Describe the purpose of the struts-config.xml file.
Expected from candidate: Demonstrate knowledge of configuration-centric Struts applications.
Example Answer: “The struts-config.xml file holds the core application configuration, including form beans, global forwards, action mappings, and controller settings. It allows developers to manage request flow and component interactions from a single centralized file.”
4) Can you explain the role of ActionForm and when you would use it?
Expected from candidate: Understand form handling and validation.
Example Answer: “ActionForm is a JavaBean used to capture and validate user input before it reaches the Action class. It is used when an application requires structured form data and input validation before the controller processes the request.”
5) Tell me about a time you resolved a challenging issue in a Struts-based application.
Expected from candidate: Ability to overcome technical obstacles.
Example Answer: “In my previous role, I encountered an issue where form validation was not triggering correctly due to an incorrect mapping in the struts-config.xml file. I traced the problem using detailed logging, corrected the mapping, and enhanced the validation logic to prevent similar issues from reoccurring.”
6) How do you ensure code quality and maintainability when working on a legacy Struts application?
Expected from candidate: Demonstrate best practices for older frameworks.
Example Answer: “I focus on modularizing Action classes, removing duplicated logic, and adding clear documentation. I also introduce unit tests to verify business logic. These practices help improve stability and reduce risk in legacy environments.”
7) Imagine that a user report shows that form data is not being submitted correctly. How would you troubleshoot this in Struts?
Expected from candidate: Logical debugging steps.
Example Answer: “I would begin by verifying that the form fields match the ActionForm property names. Then I would check the action mapping in struts-config.xml to ensure that the form bean is correctly associated. If needed, I would enable debugging logs to trace request parameters and identify where the data flow breaks.”
8) How do you handle tight deadlines when multiple Struts modules require updates?
Expected from candidate: Ability to prioritize and remain organized under pressure.
Example Answer: “At a previous position, I handled this situation by breaking tasks into smaller deliverables, prioritizing based on business impact, and communicating status updates to stakeholders. This approach ensured that all modules received attention without compromising quality.”
9) How would you migrate a Struts application to a more modern framework such as Spring MVC?
Expected from candidate: Understanding migration strategy and risk mitigation.
Example Answer: “I would first assess the existing modules to identify dependencies and complexity. Then I would design an incremental migration strategy that replaces Struts controllers with Spring components while keeping the application functional. Proper documentation and testing would ensure a smooth transition.”
10) Can you describe a situation where you collaborated with cross-functional teams to improve a Struts application?
Expected from candidate: Communication, teamwork, and cross-team coordination skills.
Example Answer: “At my previous job, I collaborated with QA, UI designers, and backend developers to optimize request handling in a Struts module. Our coordination improved the response time, enhanced the UI flow, and reduced defects in the subsequent release.”
