6 – Java Program Structure

Selenium Class 6 – Java Program Structure

i) Java Program Structure
ii) Java Sample Program

i) Java Program Structure

1) Documentation Section

It includes the comments to tell the program’s purpose, it improves the readability of the program

2) Package Statement

It includes statement that provides a package declaration

3) Import Statement/s

We import predefined and user defined libraries using “import” keyword

Ex:
import java.io.Console;

java – Project
io – Package
Console – Class

import java.io.; java – Project io – Package io. – import all classes from io package

Predefined/Built-in,
All libraries in Java are predefined, but a few libraries only automatically loaded in every Java program.

4) Class Definition
Ex:
public class Sample{
.
}

5) Interface Section
It includes method declaration

6) main Method (java program execution starts from main method)

public static void main (String [] args){
….
}

public – Access Modifier
static – Non Access Modifier (use main Method without invoking any Object)
void – Returns nothing
main – Method name

(String [] args) -?

7) Declaration Statement/s

We declare Variables and Constants

int a;
a=100;

int b=200;
b=300;
c=400;

final int y=1000; (Constant)
y=2000; //Incorrect

Variables vs. Constants

int a;//Correct
a=10;
a=30;
int b=200;
b=400;

final int x; //Incorrect
final int y=300; //Correct
y=300; //Incorrect

8) Normal Statements
c=a+b;
System.out.println(“Hello”);
System – Predefined Class
out – Object
println – Method
“Hello” – Message

9) Code Blocks

Conditions,
Loops,
Methods, etc…

10) Object Creation Statement

Note 1: We can create Object at beginning of the program or middle of the program or end of the program

Note 2: Usually we create Object/Instance of the Class within main method, but we can also create Objects outside of the main method

Syntax:
ClassName objectName= new ClassClassName();

ii) Java Sample Program

//It is a Sample Program to Understand the Java program Structure and Syntax.
package abcd;

public class Sample {
//Create a Method with Arguments and return a value (Non Static method)
public int add(int a, int b){
int result;
result=a+b;
return result;
}
//Create a method without Arguments and returns nothing (Non Static method)
public void comparison(){
int x=100, y=20;

if (x>y){
System.out.println(“X is a Big Number”);
}

else{
System.out.println(“Y is a Big Number”);
}
}
//Create a Method with Arguments and return a value (Static method)
public static int sub(int a, int b){
int result=a-b;
return result;
}
//Create a Method without and returns nothing (Static method)
public static void comparision2(){
int a=100, b=200;

if (a>b){
System.out.println(“A is a Big Number”);
}
else{
System.out.println(“B is a Big Number”);
}
}
public static void main (String [] args){
//Create Object to call Non Static methods
Sample obj = new Sample();
int res = obj.add(100, 200);
System.out.println(res);//300
//Or
System.out.println(obj.add(100, 200));//300

obj.comparison();//X is a Big Number

//Call Static Methods using Class name
res = Sample.sub(100, 50);
System.out.println(res);//50
//Or
System.out.println(Sample.sub(200, 100));//100

Sample.comparision2();//B is a Big Number

//Call Static Methods without using Class name
int x= sub(10, 5);
System.out.println(x);//5

System.out.println(sub(20,10));//10

comparision2();//B is a Big Number

int a;//Variable Declaration
a=100; //Initialization
int b=200; //Variable Declaration with Initialization
int c, d, e; //Declare multiple variables
int f=40, g=50, h=60; //Declare multiple variables with initialization

double l=123.45678;
char m=’*’;
boolean p=true;
String q=”Selenium Testing”;

System.out.println(q);//Selenium Testing
System.out.println(l);//123.45678
System.out.println(“Hello Java”);

final int price =100;
System.out.println(price);

if (a>b){
System.out.println(“A is a Big Number”);
}
else
{
System.out.println(“B is a Big Number”);
}

char grade =’U’;
switch (grade){
case ‘A’:
System.out.println(“Excellent”);
break;
case ‘B’:
System.out.println(“Good”);
break;
case ‘C’:
System.out.println(“Better”);
break;

default:
System.out.println(“Invalid Grade”);
}

//Print 1 to 5 Numbers except 4 using for loop
for (int i=1; i<=5; i++){
if (i != 4) {
System.out.println(i);
}
}
//Print 1 to 5 numbers using while loop
int j=10;
while (j<=15){
System.out.println(j);
j++;
}

//do while loop
int k=100;
do
{
System.out.println(k);
k++;
} while (k<=8);

//Enhanced for loop
String [] tools ={“Selenium”, “UFT”, “RFT”, “SilkTest”};

for (String mytool: tools){
System.out.println(mytool);
}
}
}