java source code by CodeWithHarry

package com.codewithharry;

import java.util.Scanner;

public class Main {

static int sum(int a, int b){

return a+b;

}

public static void main(String[] args) {

// Write your code here

// System.out.println("Hello World");

/* Variables

Just Like:

-Water - Bucket

-Masala - box

-Lunch - LunchBox

In Java:

Variables are containers which store data values

String, int, float, char, boolean

How to declare variables:

syntax - <dataType> <variableName> = <value>;

String name = "Harry";

String channel = "CodeWithHarry";

// System.out.println(name);

// System.out.println(name.length());

// System.out.println(name.toUpperCase());

// System.out.println(name.toLowerCase());

// System.out.println(name + " from\" " + channel);

// System.out.println(name + " from\\ " + channel);

// System.out.println(name + " from\t " + channel);

// System.out.println(name + " from\n " + channel);

// System.out.println(name.contains("Har"));

// System.out.println(name.charAt(2));

// System.out.println(name.endsWith("ry"));

// System.out.println(name.indexOf("rry"));

int numb1 = 4, numb2 = 7;

// System.out.println(Math.max(numb1, numb2));

// System.out.println(Math.min(numb1, numb2));

// System.out.println(Math.sqrt(36));

// System.out.println(Math.abs(-36));

// System.out.println(Math.abs(6));

// System.out.println(Math.random());

// System.out.println(4+(8-4)*Math.random());

int a = 45, x=56, y=67;

float b = 45.22f;

boolean isAdult = false;

// System.out.println(x);

// System.out.println(b);

// System.out.println(isAdult);

/* Rules for constructing name of variables in Java

1. Can contain digits, underscores, dollar signs, letters

2. Should begin with a letter, $ or _

3. Java is case sensitive language which means that

harry and Harry are two different variables altogether.

4. Should not contain whitespaces

5. You cannot use reserved keywords from Java

Two types of Java Data Types:

1. Primitive - byte (1 byte), short (2 bytes), int(4 bytes), long (8 bytes), float(4 bytes),

double (8 bytes), boolean(1 bit), char (2 bytes).

2. Non Primitive or Reference Data Type -

byte u = -56;

double d = 45.635435345d;

// System.out.println(d);

char grade = 'A';

// System.out.println(grade);

/* Operators in Java

Operand, operator, Operand = Result

4 + 7 = 11

Types of operators in Java

Arithmetic operators

Assignment operators

Logical Operators

Comparison Operators

int num1 = 45, num2=78;

num1 += 3;

num2 -= 8;

// Explore these operators - *=, /=, %=

// System.out.print("The value of num1 + num2 is ");

// System.out.println(num1 + num2);

// System.out.print("The value of num1 - num2 is ");

// System.out.println(num1 - num2);

// System.out.print("The value of num1 * num2 is ");

// System.out.println(num1 * num2);

// System.out.print("The value of num1 / num2 is ");

// System.out.println(num1 / num2);

// System.out.print("The value of num1 % num2 is ");

// System.out.println(num1 % num2);

// System.out.println(num2++);

// System.out.println(++num1);

// System.out.println(num1--);

// System.out.println(--num1);

* Comparison Operators:

* 1. == : checks for equality of two values

* 2. != : checks if two values are not equal

* 3. <

* 4. >

* 5. <=

* 6. >=

* Logical Operators:

* 1. && - Logical and operator - returns true only if both conditions are true

* 2. || - Logical or operator - returns true if any one condition is true

* 3. ! - Logical not - Reverse the result from true to false and vice versa

* */

// Taking user input in Java

// Scanner scan = new Scanner(System.in);

// System.out.println("Enter Your Age");

// int age = scan.nextInt();

// System.out.println(input);

// If-else conditionals

// if(age>20){

// System.out.println("You are an adult");

// }

// else if(age>5){

// System.out.println("You are not a kid");

// }

// else{

// System.out.println("You are a kid");

// }

// Switch statement in Java

// switch (age){

// case 12:

// System.out.println("You are 12 years old");

// break;

// case 56:

// System.out.println("You are 56 years old");

// break;

// case 16:

// System.out.println("You are 16 years old");

// break;

// default:

// System.out.println("You did not match any of the cases");

// }

// Quick Quiz: print sunday to saturday based on numbers 1 to 7 typed by the user

// Loops

While Loop

while(condition){

// This code will keep executing until the condition is true

}

// int i = 0;

// while(i<100){

// System.out.println(i);

// i += 1;

// }

Do While Loop

do{

// This code will keep executing until the condition is true

}while(condition)

// int j = 0;

// do{

// System.out.println(j);

// j += 1;

// }while(j>100);

For Loop

for(st1;st2;st3){

//Code to be executed

}

// for(int i=0;i<=10;i++){

// if(i==2){

// continue;

// }

//// else{

//// System.out.println(i);

//// }

// System.out.println(i);

// }

// Java Arrays

// int [] marks = {1,2,3,5};

// marks[3] = 34; // this will update marks[3]

// System.out.println(marks[0]);

// System.out.println(marks[3]);

// // Classical way to iterate an array

// for(int i=0;i<marks.length;i++){

// System.out.println(marks[i]);

// }

// System.out.println("This is for each loop:");

// // For each loop

// for(int value:marks){

// System.out.println(value);

// }

// int [][] matrix = {{1,2,3},

// {4,5,6}};

// System.out.println(matrix[0][1]);

// String [] cars = {"Maruti Harry", "Maruti", "Suzuki", "Innova", "Ford Titanium"};

// for(String value:cars){

// System.out.println(value);

// }

// Try - Catch

// String [] cars = {"Maruti Harry", "Maruti", "Suzuki", "Innova", "Ford Titanium"};

// try{

// System.out.println(cars[3]);

// }

// catch(Exception e){

// System.out.println(e);

// }

// System.out.println("Masoom");

// System.out.println(sum(5, 7));

float number_1, number_2;

System.out.println("Enter first number");

Scanner scan = new Scanner(System.in);

number_1 = scan.nextFloat();

System.out.println("Enter second number");

// Scanner scan2 = new Scanner(System.in);

number_2 = scan.nextFloat();

System.out.print("You have Entered ");

System.out.print(number_1);

System.out.print(" and ");

System.out.println(number_2);

String prompt = "Enter 0 for addition, 1 for " +

"subtraction, 2 for multiplication and 3 for division";

System.out.println(prompt);

int input = scan.nextInt();

switch (input){

case 0:

System.out.println("Adding these numbers");

System.out.print("The result is: ");

System.out.println(number_1 + number_2);

break;

case 1:

System.out.println("Subtracting these numbers");

System.out.print("The result is: ");

System.out.println(number_1 - number_2);

break;

case 2:

System.out.println("Multiplying these numbers");

System.out.print("The result is: ");

System.out.println(number_1 * number_2);

break;

case 3:

System.out.println("Dividing these numbers");

System.out.print("The result is: ");

System.out.println(number_1 / number_2);

break;

default:

System.out.println("Invalid input");

}

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java source code by CodeWithHarry

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