Structure Of The Java Program

Java program may contain several class and interface , java programs structure is defined below

package <pkgname>;//user define package

import <pkgname.classname>;

import  <pkgname.*>;

import <outerpackname.innerpackname.*>;

<modifier> class <classname>

{

        data member decl&init;

        member fn defn

 }

Packages In Java ?

package:-

        It is a collection of related classes, interfaces and sub packages.

Available packages in corejava:-

import java.lang.*;  (It is a default package)

        " * " means that all the classes and interfaces.

java.io.*; (I/O classes are defined)

java.applet.*; (Applet class is defined)

java.awt.*; (UI components are defined)

java.awt.event.*; (Event handling classes are defined)

java.net.*; (networking classes defined)

java.sql.*; (classes to access database)

java.util.*; (classes to store collection of objects)

java.text.*; (classes for formatting the text)

javax.swing.*; (advanced package of AWT)

java.rmi.*; (classes to develop distributed appln)

Installing And Running Java Program

When you are going to run java program into your system, you need to install the required application.

JDK(Java Development Kit) 1.0 to 1.8(version)

        It contains several tools to develop a java program.
javac               - java compiler
java                 - java interpreter(JVM)
javap               -to disassemble a class file into human readable                                  format.
appletviewer   -to execute applet class file.
javadoc javahjava-rmi