22
2012
JSP Interview Questions Part-2
An article by webdagger
JSP Interview Questions and Answers:
Explain the life-cycle mehtods in JSP?
Answer :: THe generated servlet class for a JSP page implements the HttpJspPage interface of the javax.servlet.jsp package. Hte HttpJspPage interface extends the JspPage interface which inturn extends the Servlet interface of the javax.servlet package. the generated servlet class thus implements all the methods of the these three interfaces. The JspPage interface declares only two mehtods – jspInit() and jspDestroy() that must be implemented by all JSP pages regardless of the client-server protocol. However the JSP specification has provided the HttpJspPage interfaec specifically for the JSp pages serving HTTP requests. This interface declares one method _jspService().
- The jspInit()- The container calls the jspInit() to initialize te servlet instance.It is called before any other method, and is called only once for a servlet instance.
- The _jspservice()- The container calls the _jspservice() for each request, passing it the request and the response objects.
- The jspDestroy()- The container calls this when it decides take the instance out of service. It is the last method called n the servlet instance. ….
What are implicit objects? List them?
Answer :: Certain objects that are available for the use in JSP documents without being declared first. These objects are parsed by the JSP engine and inserted into the generated servlet. The implicit objects re listed
- below
- request
- response
- pageContext
- session
- application
- out
- config
- page
- exception
What is a Scriptlet?
Answer :: A scriptlet can contain any number of language statements, variable or method declarations, or expressions that are valid in the page scripting language.Within scriptlet tags, you can
- Declare variables or methods to use later in the file (see also Declaration).
- Write expressions valid in the page scripting language (see also Expression).
- Use any of the JSP implicit objects or any object declared with a <jsp:useBean> tag. You must write plain text, HTML-encoded text, or other JSP tags outside the scriptlet.
Scriptlets are executed at request time, when the JSP engine processes the client request. If the scriptlet produces output, the output is stored in the out object, from which you can display it. ….
What is a Declaration?
Answer :: A declaration declares one or more variables or methods for use later in the JSP source file. A declaration must contain at least one complete declarative statement. You can declare any number of variables or methods within one declaration tag, as long as they are separated by semicolons. The declaration must be valid in the scripting language used in the JSP file.
<%! somedeclarations %>
<%! int i = 0; %>
<%! int a, b, c; %>
What is Expression?
Answer :: 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. Because the value of an expression is converted to a String, you can use an expression within text in a JSP file. Like
<%= someexpression %>
<%= (new java.util.Date()).toLocaleString() %>
You cannot use a semicolon to end an expression ….
What is a Hidden Comment?
Answer :: A comments that documents the JSP page but is not sent to the client. The JSP engine ignores a hidden comment, and does not process any code within hidden comment tags. A hidden comment is not sent to the client, either in the displayed JSP page or the HTML page source. The hidden comment is useful when you want to hide or “comment out” part of your JSP page.
You can use any characters in the body of the comment except the closing –%> combination. If you need to use –%> in your comment, you can escape it by typing –%\>.
JSP Syntax
<%– comment –%>
Examples
<%@ page language=”java” %>
<html>
<head><title>A Hidden Comment </title></head>
<body>
<%– This comment will not be visible to the colent in the page source –%>
</body>
</html> ….
What is a output comment?
Answer :: A comment that is sent to the client in the viewable page source.The JSP engine handles an output comment as uninterpreted HTML text, returning the comment in the HTML output sent to the client. You can see the comment by viewing the page source from your Web browser.
JSP Syntax
<!– comment [ <%= expression %> ] –>
Example 1
<!– This is a commnet sent to client on
<%= (new java.util.Date()).toLocaleString() %>
–>
Displays in the page source:
<!– This is a commnet sent to client on January 24, 2004 –>
Related Posts
A Word From Author:
We share articles collected from the web.Any suggestions or issues with the contents please contact us at info@downloadsparade.com.Please read Disclaimer For more Information.
Leave a comment
Tutorials & Interview Questions
E-Books of the month
A limited time offer only for one month.The Books are Guide to HTML, JavaScript and PHP For Scientists and Engineers & Sams Teach Yourself is a Book in which you can learn the c++ within 24 hours...
Enter your Email to Grab free E-Books
didn't receive the e book please contact us at info@downloadsparade.com
Recent Comments
- uma on Tally Tutorial Part-1
- Sudheer.Choragudi on IOS Commands
- Sudhakar Singajogi on QTP Tutorial for Beginners Part-2
- webdagger on OSI LAYERS
- kaladhar on OSI LAYERS
- sreekanth on SAP Tutorial Part-5
Who's Online
- 0 Members.
- 3 Guests.
