CS506 Final Term Solved Subjective with References by Moaaz

Solved Subjective · From Final term Papers · JULY 05,2012 · PSMD01 · Write 2 Characteristics of Expression Language. (2 Mark)

Answer: (Page 459) Multiple expressions can be combined and intermixed with static text. For example $ { ―Hello‖ ${user.firstName} ${user.lastName} }

Most importantly, if object/identifier is null, no NullPointerException would be thrown☺. For example. If the expression written is: ${person.name}

Why yield( ) method use? (2 Mark)

Answer: (Page 237)

•  Allows any other threads of the same priority to execute (moves itself to the end of the priority queue)
•  If all waiting threads have a lower priority, then the yielding thread resumes execution on the CPU

What is the hidden comment in JSP? (2 Mark)

A comment that documents the JSP page but is not sent to the client. Examples :- <% page language="java" %>

Which method of ResultSetMetaData object is used to return the suggested column label for print out? (2 Mark)

Answer: (Page 175) The getColumnLabel() method returns the suggested column label for printouts

What is the purpose of wait( ) , notify( ) and notifyAll( ) methods? (3 Mark)

The wait(),notify(), and notifyAll() methods are used to provide an efficient way forthreads to wait for a shared resource. When a thread executes an object's wait() method, itenters the waiting state. It only enters the ready state after another thread invokes theobject's notify() or notifyAll() methods..

What are the three stages of Servlet Lifecycle? (3 Mark)

Answer: (Page 267) A servlet passes through the following stages in its life. Initialize Service Destroy

Advantages of using Custom Tags? (3 Mark)

Answer: (Page 379)

•  Provides cleaner separation of processing logic and presentation, than JavaBeans.
•  Have access to all JSP implicit objects like out, request etc.
•  Can be customized by specifying attributes.

How JSF does provide Navigation? (3 Mark)

Answer: (Page 487) Page navigation determines the control flow of a Web application. JSF provides a default navigational handler and this behavior can be configured in configuration file.

Difference between static and non static inner class? (3 Mark)

A non-static inner class may have object instances that are associated with instances of the class's outer class. A static inner class does not have any object instances.

Which Five operators are used in Expression Language? (5 Mark)

Expression language can use the following five arithmetic operators to act on integer and floating point values: + operator for addition

• operator for subtraction

* operator for multiplication / operator for division % operator for remainder

What is Expression in JSP? Give an example. (5 Mark)

Answer: (Page 335) The format of writing a Java expression is: <%= Java expression %> These expressions are evaluated, after converted to strings placed into HTML page at the place it occurred in JSP page Examples of writing Expressions are:

<h2> Time: <%= new java.util. Date() %> </h2> will print current data & time after converting it to String

<h2> Welcome: <%= request.getParameter(―name‖)%> </h2> will print the name attribute

Difference between ServletContext and ServletConfig? (5 Mark)

ServletConfig is a servlet configuration object used by a servlet container used to pass information to a servlet during initialization. All of its initialization parameters can ONLY be set in deployment descriptor. The ServletContext object is contained within the ServletConfig object, which the Web server provides the servlet when the servlet is initialized.

You can specify param-value pairs for ServletContext object in <context-param> tags in web.xml file.

The ServletConfig parameters are specified for a particular servlet and are unknown to other servlets. The ServletContext parameters are specified for an entire application outside of any particular servlet and are available to all the servlets within that application.

ServletConfig defines an object generated by a servlet engine. ServletContext defines an object to be created by a servlet engine.

• Disadvantage of Page-centered approach (2 marks)

Answer: (Page 411) The page-centric approach has lot of draw backs such as the code becomes a mixture of presentation, business and data access logic. The maintenance and up-gradation of the application becomes a nightmare.

• Methods of session tracking (2 marks)

Answer: (Page 297) Cookies

• What does finalization means? (2 marks)

Answer: (Page 47) When a finalize method is defined in a class, Java run time calls finalize() whenever it is about to recycle an object of that class.

• What does error 404 display? (3 marks)

Answer: (Page 244) Indicates that the requested resource is not available.