Programming Structure of JAVA

Every language has fixed program structure which must be followed to develop program in that language. Java has also a definite program structure which are as follows.

Ø  Documentation Section                            -           Optional

Ø  Package Declaration Section                    -           Optional

Ø  Import Section                                          -           Essential

Ø  Interface Declaration Section                   -           Optional

Ø  User-defined Class Declaration Section   -           Optional

Ø  Main Class Declaration Section               -           Essential

Documentation Section :-

                In this section, we write the Commented Statements. It represents some extra information about our program or statement.

                        Any statement written within either of two symbols i.e. // or /* …….....*/ is called Commented Statement.

a.       // :- It can comment single line.

              Ex:-     //…………………..

                          //…………………..

                          //…………………..

b.      /*……….*/ :- It can comment multiple lines.

              Ex:-     /*………………

                          ………………...

                          ……………….*/

Commented statements are ignored by the compiler thus, it cannot be seen at run-time.

Package Declaration Section :-

                In this section, we create user-defined package.

                Package is a collection of several Classes.

Import Section :-

                In this section, We include the pre-defined packages and Classes. So, we could use the pre-defined methods.

                As we known that, class is a container of holding different methods and package is a container of holding different Classes.

The syntax of importing a package and Classes is as follows :-

                import java.packagename.classname;

                import. java.packagename.*;

                import java.packagename.classname.methodname;

Here, java is superpackage.

The list of Some pre-defined API package are as follows –

1. java.lang.*;       -     Standard package (By default imported).
2. java.io.*;
3. java.util.*;
4. java.net.*;
5. java.awt.*;
6. java.applet.*;
7. javax.swing.*;

Interface Declaration Section :-

         In this section, we create an Interface. “Interface” is just Class like entity which is used to implement the multiple Inheritance.

User-defined Class Declaration Section :-

            In this section, we can create any number of users defined Classes.

Main Class Section :-

          It is essential part of Java program. In this section, We create the main class. A Class, in which main( ) method reside, is called Main Class.

The syntax of create a main Class is as follows :-

                Class <Classname>

                {

                        public static void main(String args[ ])

                        {

                                    …………………

                                    …………………

                        }

                }