JAVA Interview Questions and Answers in 2025 (100+ Q&A)

Jsp

Ques:- How can the output of JSP or servlet page be prevented from being cached by the browser?

Asked In :-

Right Answer:
To prevent the output of a JSP or servlet page from being cached by the browser, you can set the appropriate HTTP headers in your response. Use the following code in your JSP or servlet:

```java
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate"); // HTTP 1.1
response.setHeader("Pragma", "no-cache"); // HTTP 1.0
response.setDateHeader("Expires", 0); // Proxies
```

This will instruct the browser not to cache the page.

Jsp

Ques:- Explain JSP directives.

Asked In :- Girmiti Software,

Right Answer:
JSP directives are special instructions that provide global information about an entire JSP page. They are defined using the `<%@ ... %>` syntax and can include three main types:

1. **Page Directive**: Defines page-level attributes like content type, language, and error handling.
Example: `<%@ page contentType="text/html;charset=UTF-8" language="java" %>`

2. **Include Directive**: Includes a file at translation time, allowing for code reuse.
Example: `<%@ include file="header.jsp" %>`

3. **Taglib Directive**: Declares a tag library, enabling the use of custom tags in the JSP.
Example: `<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>`

Jsp

Ques:- Why does _jspService() start with an underscore, while other lifecycle methods do not?

Asked In :- Cateina Technologies, TechFerry Infotech, endeca, magneto it solutions,

Right Answer:

The `_jspService()` method starts with an underscore to indicate that it is a private method generated by the JSP compiler, while other lifecycle methods like `init()` and `destroy()` are public and defined by the servlet lifecycle.

Jsp

Ques:- Define Expression

Asked In :- RoboSoft,

Right Answer:
In JSP, an expression is a piece of code that evaluates to a value and is used to output data to the client. It is written within `<%= %>` tags, allowing dynamic content to be displayed on the web page.

Jsp

Ques:- Can Static method be Override?

Asked In :- Shipmnts, Hestabit Technologies, RND Softech, 6d technologies, jktech,

Right Answer:
No, static methods cannot be overridden because they are bound to the class, not the instance.

Jsp

Ques:- What are standard actions in JSP?

Asked In :- Mitsogo Technologies, Yotta Techports, Torry Harris Integration Solutions, cambridge mobile telematics,

Right Answer:
Standard actions in JSP are predefined tags that perform specific tasks, such as:

1. `<jsp:include>` - Includes a file at request time.
2. `<jsp:forward>` - Forwards a request to another resource.
3. `<jsp:useBean>` - Instantiates a JavaBean or retrieves an existing one.
4. `<jsp:setProperty>` - Sets properties of a JavaBean.
5. `<jsp:getProperty>` - Retrieves properties from a JavaBean.
6. `<jsp:plugin>` - Embeds an applet or a JavaBean in the page.
7. `<jsp:element>` - Allows dynamic creation of XML elements.

These actions help in managing the flow of control and data in JSP applications.

Jsp

Ques:- How can a thread safe JSP page be implemented?

Asked In :- workspan,

Right Answer:
A thread-safe JSP page can be implemented by using the following approaches:

1. **Use the `synchronized` keyword**: Wrap the code in scriptlets or methods that modify shared resources with `synchronized` blocks.

2. **Avoid scriptlets**: Use JavaBeans or custom tags to encapsulate logic and state, minimizing shared state.

3. **Use session scope**: Store mutable objects in the session scope instead of request scope to avoid concurrent access issues.

4. **Implement `HttpServlet`**: Instead of using JSP directly, handle requests in a servlet and forward to JSP for rendering, managing concurrency in the servlet.

5. **Use the `@WebServlet` annotation**: If using annotations, ensure the servlet is configured to handle requests in a thread-safe manner.

By following these practices, you can ensure that your JSP page is thread-safe.

Jsp

Ques:- Explain the various scope values for tag.

Asked In :- Paktolus Solutions,

Right Answer:
In JSP, the various scope values for tags are:

1. **page**: The scope is limited to the current JSP page.
2. **request**: The scope is available for the duration of a single HTTP request.
3. **session**: The scope is available for the duration of a user's session.
4. **application**: The scope is available for the entire application, shared across all users and sessions.

Jsp

Ques:- Define JSP Scriptlet.

Asked In :- AROHA TECHNOLOGIES, COGNISOFT TECHNOLOGIES, nendrasys,

Right Answer:
A JSP scriptlet is a block of Java code embedded within HTML in a JSP file, enclosed by `<%` and `%>` tags, which allows dynamic content generation on the server side.

Jsp

Ques:- Explain pge Directives.

Asked In :- Quarks Technosoft, PRIMUS Global Technologies, transunion, pna group,

Right Answer:
Page directives in JSP (JavaServer Pages) are special instructions that provide global information about an entire JSP page. They are defined using the `<%@ ... %>` syntax and can control various aspects of the page, such as:

1. **page**: Defines page-level attributes like content type, language, and error handling.
2. **include**: Includes other files at translation time.
3. **taglib**: Declares a tag library to use custom tags in the JSP.

For example:
```jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ include file="header.jsp" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
```

Jsp

Ques:- Differentiate between and .

Asked In :- sbl,

Right Answer:
`<jsp:include>` is used to include a file at request time, meaning the included file is processed and its output is sent to the client as part of the response. Changes in the included file will reflect immediately.

`<jsp:forward>` is used to forward the request to another resource (like a JSP or servlet) on the server. The original request is replaced by the forwarded request, and the client is not aware of this change.

Jsp

Ques:- How can I maintain session in JSP Page in the bases of user name and password:

Asked In :- AROHA TECHNOLOGIES, appway, neogov,

Right Answer:
To maintain a session in a JSP page based on username and password, you can use the following steps:

1. **Create a Login Form**: Use an HTML form to collect the username and password.
2. **Process the Login**: In a JSP page, retrieve the username and password from the request parameters.
3. **Validate Credentials**: Check the credentials against a database or predefined values.
4. **Create a Session**: If the credentials are valid, create a session using `request.getSession()` and store the username in the session.

Example code snippet:

```jsp
<%
String username = request.getParameter("username");
String password = request.getParameter("password");

// Validate credentials (this is just an example)
if ("validUser".equals(username) && "validPass".equals(password)) {
HttpSession session = request.getSession();
session.setAttribute("username", username);
response.sendRedirect("welcome.jsp"); // Redirect to a

Jsp

Ques:- How to restrict page errors display in a JSP page?

Asked In :- rapidera technologies, Axiscades Engineering Technologies,

Right Answer:
To restrict page errors display in a JSP page, you can use the following directive at the top of your JSP file:

```jsp
<%@ page errorPage="error.jsp" isErrorPage="false" %>
```

Additionally, you can configure the web.xml file to handle errors globally by defining error pages:

```xml
<error-page>
<error-code>500</error-code>
<location>/error.jsp</location>
</error-page>
```

Jsp

Ques:- Explain client and server side validation?

Asked In :-

Right Answer:
Client-side validation occurs in the user's browser before the data is sent to the server, using technologies like JavaScript to check for errors and improve user experience. Server-side validation happens on the server after the data is submitted, ensuring that the data is correct and secure before processing it, regardless of the client-side checks.

Jsp

Ques:- What is the requirement of a tag library?

Asked In :- Sumedha Softech, Singsys, ITOrizon, sso, brainium information technologies pvt. ltd.,

Right Answer:
A tag library in JSP is required to encapsulate reusable components and custom tags, allowing developers to create dynamic web content more easily and maintainably by separating presentation logic from business logic.

Jsp

Ques:- Explain jsp:plugin action?

Asked In :- QuantumLink,

Right Answer:
The `<jsp:plugin>` action is used in JSP to embed Java applets or JavaBeans in a web page. It generates the necessary HTML code to include the Java plugin in the browser, ensuring that the required Java runtime environment is available for the applet or bean to function correctly.

Jsp

Ques:- Explain the advantages of jsp?

Asked In :- Avizva Solutions, Cyzerg, t-systems,

Right Answer:
1. **Separation of Concerns**: JSP allows separation of HTML and Java code, making it easier to manage and maintain.
2. **Ease of Use**: It uses simple tags and expressions, making it user-friendly for developers.
3. **Integration with Java**: JSP is built on Java, allowing easy integration with Java libraries and frameworks.
4. **Reusable Components**: Supports custom tags and reusable components, enhancing modularity.
5. **Automatic Compilation**: JSP pages are automatically compiled into servlets, simplifying deployment.
6. **Support for JavaBeans**: Easily integrates with JavaBeans for dynamic content generation.
7. **Rich Tag Libraries**: Offers various tag libraries (like JSTL) for common tasks, reducing code complexity.
8. **Platform Independence**: Being Java-based, JSP can run on any platform that supports Java.

Jsp

Ques:- Explain static method?

Asked In :- Atypon Systems, Karza Technologies, SightSpectrum Technology Solutions (P),

Right Answer:
A static method is a method that belongs to the class rather than any specific instance of the class. It can be called without creating an object of the class and can only access static variables and other static methods within the class.

Jsp

Ques:- What are the lifecycle phases of a jsp?

Asked In :- bluestacks,

Right Answer:
The lifecycle phases of a JSP are:

1. **Translation Phase**: The JSP is translated into a servlet.
2. **Compilation Phase**: The generated servlet is compiled into bytecode.
3. **Loading Phase**: The servlet class is loaded into memory.
4. **Instantiation Phase**: An instance of the servlet is created.
5. **Initialization Phase**: The `init()` method is called to initialize the servlet.
6. **Request Processing Phase**: The `service()` method is called to handle requests.
7. **Destruction Phase**: The `destroy()` method is called before the servlet is removed from memory.

Jsp

Ques:- How is jsp used in the mvc model?

Asked In :- Evince Development, Concerto Software, MSC Technologies, tvs next, logic-fruit technologies,

Right Answer:
JSP (JavaServer Pages) is used in the MVC (Model-View-Controller) model as the View component. It is responsible for presenting data to the user, while the Controller handles user input and interactions, and the Model manages the data and business logic. JSP pages retrieve data from the Model through the Controller and display it to the user.

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