Arrays are data structures that hold a group of elements and each element has a position denoted by an integer called the index of that element.  

Important properties of arrays

Important properties of arrays are:

1. Array indexes (element positions) have to be integers and start at 0. 

1. How can you call a JSP page using a request dispatcher?

2. How can you suppress direct access to a JSP file through a client request?

1. What are the three ways in which you can tell the container that your class is a servlet?

2. Compare filters with RequestDispatcher mechanism.

3. Can you include or forward to filters using the RequestDispatcher mechanism?

4. What will happen if you call two RequestDispatcher forwards or includes from within a servlet's doXXX method?

5. Can you use wrappers to have two RequestDispatcher forward requests without any exception?

There is a class in Java called Object and is present in the package java.lang.Object. This is different from the concept of objects in object oriented programing, and begenners may get confused. Note that is is just a class in Java with the name as Object. 

Object class API basics

• Class java.lang.Object is the root of the class hierarchy in Java.

• Every class has Object as a superclass either directly or indirectly.

The while statement

The “while loop” is an alternative to “for loop”. a “for loop” is usually used when the number of times the block is to be executed is known. A “while loop” is usually used when the number of times the block is to be executed is not known, like prompting the user whether to stop executing during every iteration.

The syntax of “while loop” is:

while (<condition>) <statements>;

Example: