How
to Install Java
Steps to follow: ----
www.java.sun.com-----DownLoads----Click
and Again click in the same place---One
POPUp window comes----Click---downlods----rightside-----popular downloads-----java
for developers-----click---Javadownload (first tab)-----select accept licence
agreement option button---select windowsi586(for 32 bit
computer)----select-----then one window
comes----jdk-7-window-i586.exe---savefile---then installation starts-----after
finishing this ----whereever we want we can copy and paste that donloaded
folder----then doubleclick on the folder—next---next-----finish
After
the installation it creates one folder structure: ----
C:\
ProgramFiles
Java
Bin
Lib
Examples
Jre7
Jdk
folder consists of subfolders lie bin, lib, jre 7 etc.
After
Installation
1. Bin: ---It consists of all the
application files which are used to compile, execute, decompile etc.
2.
Lib: -- It consists of all the
library files which give support for JAVA applications.
3.
JRE: ---JAVA runtime environment
which gives support when we are executing the program.
4.
JRE7:---It provides help to run java
applications in browsers.
5. JAVA Environment Variables: ---- This
we use to set the configuration of JAVA to local System Right click on My
computer---properties---advanced tab---Environment variables----user
variables----new—variable name---path –variable value
-- c:\programfiles\java\jdk1.7.0\bin;
Classpath---
Environment variables-------new— classpath--c:\programfiles\java\jdk1.7.0\bin\tools.jar;.;---ok.
Then goto
cmd---run—javac---enter------java---enter
HelloWorld program development
HelloWorld program development
Java Program Structure:
/**
*document type of comment
*/
Package section
Import section
Class section
{
Declaration of variables, methods, blocks….etc
main method
main method
}
Sections In Java: ---
The Java Platform Api Specification Contains The Complete Listing For All Packages, Interfaces, Classes, Fields, And Methods Supplied By The Java Se Platform. Load The Page In Your Browser And Bookmark It. As A Programmer, It Will Become Your Single Most Important Piece Of Reference Documentation.
1. Package Section: ---
What Is A Package?
A Package Is A Namespace That Organizes A Set Of Related Classes And Interfaces. Packages are Similar To Different Folders On Your Computer.
“A package consists of classes,interfaces,enums,annotations…etc ”
package com.first;--à user defined package
import java.lang.*;--àpredefined package
Class Myclass {
}
2. Import Section
Is Used to Import the Java Files Into User-Defined Program From Library.
import Java.io.*;
(Like In C We Use #Include)
3. Class Section
A Class Is The Blueprint From Which Individual Objects Are Created. There May Be Thousands Of Other Bicycles In Existence,. Each Bicycle Was Built From The Same Set Of Blueprints And Therefore Contains The Same Components. In Object-Oriented Terms, We Say That Your Bicycle Is An Instance Of The Class Of Objects Known As Bicycles.
The Class Consists Of All the Members of A Java Program.We Should Write Every Thing In The Class Only.
Main():---
Is used to write the main method logic in a program.
Writing the first Java program
Open any following Editor.
ü Notepad
ü Editor
ü Notepad++
ü Editplus
ü Eclipse/myeclipse
ü Netbeans
ü Vi(for unix)
/*
* this is my first program in java
* helloworld.java
* date:10/14/2011
* author : Kiran Kumar
*/
import java.lang.*;
class HelloWorld
{
public static void main(String [] args)
{
System.out.println(“hello world!”);
}
}
Save the above file with HelloWorld.java
To execute the program
D:\core\>javac HelloWold.java
To run
D:\core\>java HelloWold
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