JSP Interview Questions

Question: What do you understand by JSP Actions? Answer: JSP actions are XML tags that direct the server to use existing components or control the behavior of the JSP engine. JSP Actions consist of a typical (XML-based) prefix of "jsp" followed by a colo

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JSP Interview Questions

     

Question: What do you understand by JSP Actions?
Answer: JSP actions are XML tags that direct the server to use existing components or control the behavior of the JSP engine. JSP Actions consist of a typical (XML-based) prefix of "jsp" followed by a colon, followed by the action name followed by one or more attribute parameters.


There are six JSP Actions:

<jsp:include/>

<jsp:forward/>

<jsp:plugin/>

<jsp:usebean/>

<jsp:setProperty/>

<jsp:getProperty/> 

  

Question: What is the difference between <jsp:include page = ... > and 
<%@ include file = ... >
?.
Answer: Both the tag includes the information from one page in another. The differences are as follows:
<jsp:include page = ... >: This is like a function call from one jsp to another jsp. It is executed ( the included page is executed  and the generated html content is included in the content of calling jsp) each time the client page is accessed by the client. This approach is useful to for modularizing the web application. If the included file changed then the new content will be included in the output. 

<%@ include file = ... >: In this case the content of the included file is textually embedded in the page that have <%@ include file=".."> directive. In this case in the included file changes, the changed content will not included in the output. This approach is used when the code from one jsp file required to include in multiple jsp files.
  

Question: What is the difference between <jsp:forward page = ... > and
response.sendRedirect(url),?.
Answer:
The <jsp:forward> element forwards the request object containing the client request information from one JSP file to another file. The target file can be an HTML file, another JSP file, or a servlet, as long as it is in the same application context as the forwarding JSP file. 
sendRedirect sends HTTP temporary redirect response to the browser, and browser creates a new request to go the redirected page. The  response.sendRedirect kills the session variables.
 

Question: Identify the advantages of JSP over Servlet.

a) Embedding of Java code in HTML pages
b) Platform independence
c) Creation of database-driven Web applications
d) Server-side programming capabilities

Answer :- Embedding of Java code in HTML pages
  

Write the following code for a JSP page:
<%@ page language = "java" %> 

<HTML>
<HEAD><TITLE>RESULT PAGE</TITLE></HEAD>
<BODY>
<%

PrintWriter print = request.getWriter();
print.println("Welcome");

%>
</BODY>
</HTML>
Suppose you access this JSP file, Find out your answer.
a) A blank page will be displayed.
b) A page with the text Welcome is displayed
c) An exception will be thrown because the implicit out object is not used
d) An exception will be thrown because PrintWriter can be used in servlets only

Answer :- A page with the text Welcome is displayed
 

Question: What are implicit Objects available to the JSP Page?
Answer: Implicit objects are the objects available to the JSP page. These objects are created by Web container and contain information related to a particular request, page, or application. The JSP implicit objects are:

Variable
Class
Description
application
javax.servlet.ServletContext
The context for the JSP page's servlet and any Web components contained in the same application.
config
javax.servlet.ServletConfig
Initialization information for the JSP page's servlet.
exception
java.lang.Throwable
Accessible only from an error page.
out
javax.servlet.jsp.JspWriter
The output stream.
page
java.lang.Object
The instance of the JSP page's servlet processing the current request. Not typically used by JSP page authors.
pageContext
javax.servlet.jsp.PageContext
The context for the JSP page. Provides a single API to manage the various scoped attributes.
request
Subtype of javax.servlet.ServletRequest
The request triggering the execution of the JSP page.
response
Subtype of javax.servlet.ServletResponse
The response to be returned to the client. Not typically used by JSP page authors.
session
javax.servlet.http.HttpSession
The session object for the client.
 

Question: What are all the different scope values for the <jsp:useBean> tag?
Answer:<jsp:useBean> tag is used to use any java object in the jsp page. Here are the scope values for <jsp:useBean> tag:
a) page
b) request
c) session and
d) application

  

Question: What is JSP Output Comments?
Answer: JSP Output Comments are the comments that can be viewed in the HTML source file.
Example: 
<!-- This file displays the user login screen -->
and 
<!-- This page was loaded on
<%= (new java.util.Date()).toLocaleString() %> -->
 

Question: What is expression in JSP?
Answer: Expression tag is used to insert Java values directly into the output. Syntax for the Expression tag is: 
<%= expression %>
An expression tag contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. The following expression tag displays time on the output:
<%=new java.util.Date()%>
  

Question: What types of comments are available in the JSP?
Answer: There are two types of comments are allowed in the JSP. These are
hidden and output comments. A hidden comments does not appear in the generated output in the html, while output comments appear in the generated output.
Example of hidden comment:
<%-- This is hidden comment --%>
Example of output comment:
<!-- This is output comment -->
 

Question: What is JSP declaration?
Answer: JSP Decleratives are the JSP tag used to declare variables. Declaratives are enclosed in the <%! %> tag and ends in semi-colon. You declare variables and functions in the declaration tag and can use anywhere in the JSP. Here is the example of declaratives:

<%@page contentType="text/html" %>

<html>

<body>

<%!
int cnt=0;
private int getCount(){
//increment cnt and return the value
cnt++;
return cnt;
}
%>

<p>Values of Cnt are:</p>

<p><%=getCount()%></p>

</body>

</html>
  

Question: What is JSP Scriptlet?
Answer: JSP Scriptlet is jsp tag which is used to enclose java code in the JSP pages. Scriptlets begins with <% tag and ends with %> tag. Java code written inside scriptlet executes every time the JSP is invoked.
Example:
  <%
  //java codes
   String userName=null;
   userName=request.getParameter("userName");
   %
>
  

Question: What are the life-cycle methods of JSP?
Answer: Life-cycle methods of the JSP are:
a) jspInit(): The container calls the jspInit() to initialize the servlet instance. It is called before any other method, and is called only once for a servlet instance.
b)_jspService(): The container calls the _jspservice() for each request and it passes the request and the response objects. _jspService() method cann't be overridden. 
c) jspDestroy(): The container calls this when its instance is about to destroyed.
The jspInit() and jspDestroy() methods can be overridden within a JSP page.

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JSP Interview Questions

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Comments:11
sarvesh rao
December 21, 2011
jsp, servlet

Please send question.
BeesannaM
March 14, 2012
jsp-question

what is mean of page scope?how it will be use in applications..tell me the syntax of that...
BeesannaM
March 14, 2012
struts-question

What are the controls in struts technology...?
kunal
March 30, 2012
feedback

its okay okay
chandu
May 22, 2012
jsp

when do we use application scope
Nisha Sumesh
May 28, 2012
Error in page

Question: What is the difference between <jsp:forward page = ... > and response.sendRedirect(url),?. For the above question, the following line is given in the answer and i think it is wrong."The response.sendRedirect kills the session variables" . I think the value of session exists till the browser cache exists.
Nisha Sumesh
May 28, 2012
error

Question: What is the difference between <jsp:forward page = ... > and response.sendRedirect(url),?. For the above question, the following line is given in the answer and i think it is wrong."The response.sendRedirect kills the session variables" . I think the value of session exists till the browser cache exists.
chandu
July 1, 2012
servlet

what is meaning of session tracking in servlet plz replay with short description
Nettie
October 27, 2012
CeWPyrsdRREGRW

Which came first, the problem or the solution? Luckliy it doesn't matter.

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