Top questions with answers asked in MNC on Advance Java JSP

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Advanced Java JSP interview questions along with their answers:

  1. What is JSP (JavaServer Pages), and how does it differ from Servlets?
    • Answer: JSP (JavaServer Pages) is a technology used for creating dynamic web pages in Java. It allows developers to embed Java code directly into HTML pages using special tags (e.g., <% %>, <%= %>, <jsp:...>), making it easier to generate dynamic content. Unlike Servlets, which use Java code to generate HTML responses programmatically, JSP allows developers to mix Java code with HTML markup, improving code readability and maintainability.
  2. What are the main directives in JSP, and what is their purpose?
    • Answer: Directives in JSP are special instructions that provide metadata and configuration information to the JSP container. The main directives in JSP are:
      • Page Directive (<%@ page %>): Provides instructions for the JSP container, such as page encoding, session management, error handling, and buffer size.
      • Include Directive (<%@ include %>): Includes the contents of another file (e.g., HTML, JSP) into the current JSP page during translation.
      • Taglib Directive (<%@ taglib %>): Defines custom tag libraries used in the JSP page for encapsulating reusable functionality or custom behavior.
  3. What is the difference between request.getAttribute() and session.getAttribute() in JSP?
    • Answer:
      • request.getAttribute(): Retrieves an attribute stored in the request scope, which is accessible only within the current request. Data set as request attributes using request.setAttribute() method is available to other Servlets or JSP pages forwarded or included in the same request.
      • session.getAttribute(): Retrieves an attribute stored in the session scope, which persists across multiple requests and is accessible to all pages within the same session. Data set as session attributes using session.setAttribute() method remains available until the session expires or is invalidated.
  4. How can you include external resources (e.g., CSS, JavaScript) in a JSP page?
    • Answer: External resources such as CSS and JavaScript files can be included in a JSP page using the <link> and <script> HTML tags, respectively. For example:

      jsp

      <link rel="stylesheet" type="text/css" href="styles.css">
      <script src="script.js"></script>

      Additionally, JSP provides the <jsp:include> action for including other JSP pages or Servlets into the current JSP page dynamically at runtime.

  5. What is the JSP Expression Language (EL), and how is it used?
    • Answer: The JSP Expression Language (EL) is a scripting language used to access and manipulate data stored in objects (e.g., request, session, application) within JSP pages. EL expressions are enclosed within ${} syntax and are evaluated at runtime to produce dynamic values. For example:

      jsp

      <h2>Welcome, ${user.name}!</h2>
      <p>Your account balance is: ${account.balance}</p>

      EL simplifies JSP development by providing a concise syntax for accessing data and reducing the need for scriptlets or Java code in JSP pages.