Java Tutorial 1
(Java Environment Setup and Write First Java Program)
> Download Java (JDK) Software and Install
> set Environment Variable (Path Variable)
(* If want to execute Java programs from any directory in C Drive)
How to set Path Environment Variable:
OS: Windows 7
> Select MYComputer and Right click
> Properties
> Advanced System Settings
> Environment Variables
> Select “New” in System variables
> Enter Variable as “Path”
> Enter JDK bin directory path (“C:\Program Files\Java\jdk1.8.0_45\bin”) in value field
> OK > OK > Ok
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Verify the Environment setup:
> Launch Command Prompt
> Type java (It provides details)
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Three steps to write and execute Java Programs
i) Write Java Program in Notepad (Editor)
ii) Compile the Program (It creates Class file)
Command prompt > Change to Program file Directory
> Type javac Programname.java (java is extension of Java program, javac command for compilation)
iii) Run /Execute the Java Program
> Type java programName
(It provides Output on the console)
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Use Eclipse IDE to write and execute Java programs.
Eclipse IDE (Integrated Development Environment)
It is a platform to write and execute Java programs, Perl, Python, PHP, Ruby etc…
It provides Editor, context help, help for syntax errors, Auto compilation and debugging.
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Download Eclipse software and extract.
Steps:
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> Create Java Project
-> Create a Package
-> Create a Class / Interface
(We can write java code in the Class file)
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Ex:
public class Sample {
public static void main (String [] args){
System.out.println(“Hello Java and Selenium”);
}
}
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Java Program structure or Java Syntax:
1) Package declaration statement
ex:
package abcd;
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2) Import statements
we can import Built in and User defined Libraries using import keyword.
(In order to use Existing Classes, Objects, and Methods)
Example:
import java.io.console;
(It Imports Console Class only from io package)
import java.io.*;
(It imports all classes from io package)
——————
java – project
io – package
Console – Class
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3) Class declaration statement
ex:
public class Sample {
}
public – Access Modifier
class – Java keyword to declare a class
Sample – Name of the Class
Note: First letter of Class name should be upper case.
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4) Comments section
// This is a Sample Java Program
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5) Main Method
(Java program execution starts from main method.)
(Main method is mandatory in every Java program)
public static void main (String [] args) {
}
public – Access Modifier
static – use main method without invoking any object.
void – returns nothing
main – method name
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6) Declarations
We can declare variables and constants
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Normal statements
Conditional blocks
Loop blocks
Method declarations
Etc…
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Sample Java Program:
package abcd;
import java.io.Console;
import java.lang.*;
public class Sample2 {
// This is a Sample Java Program
public static void main (String [] args){
int a = 50, b, c; // Declaration of Variables
b= 20; // Initialization
System.out.println(a + b); // 70
System.out.println(“Addition of a, b is: “+ (a+b));
final int MONEY = 100; // Declaration of Constant
if (a > b) {
System.out.println(“A is a Big Number”);
}
else
{
System.out.println(“B is a Big Number”);
}
for (c = 1; c <= 10; c++){
System.out.println(c);
}
}
}
