Exercise-1: java Programming Basics

1. Write a java to Print an Integer entered by an user

Import java.util.Scanner;

public class HelloWorld {

Public static void main(String[] args) {

// creates a reader instance which takes

// input from standard input - keyboard
Scanner reader = new Scanner(System.in);
System.out.print("Enter a number: ");

// nextInt() reads the next integer from the keyboard

int number = reader.nextInt();

// println() prints the following line to the output screen

System.out.println("You entered: " + number);
}
}

Output

Enter a number: 10
You entered: 10
2. java Program to Add Two Integers

class Main {

public static void main(String[] args) {

System.out.println("Enter two numbers");

int first = 10;
int second = 20;

System.out.println(first + " " + second);

// add two numbers

int sum = first + second;
System.out.println("The sum is: " + sum);
}
}

Output:

Enter two numbers

10 20
The sum is: 30
3. Multiply Two Floating-Point Numbers

public class MultiplyTwoNumbers {

public static void main(String[] args) {

float first = 1.5f;

float second = 2.0f;

float product = first * second;

System.out.println("The product is: " + product);

}
}

Output

The product is: 3.0

4. write a JAVA program to display default value of all primitive data
type of JAVA

Aim: To write a JAVA program to display default value of all primitive data type of JAVA

Program:

class defaultdemo
{

static byte b;
static short s;

static int i;
static long l;

static float f;
static double d;

static char c;
static boolean bl;

public static void main(String[] args)

{

System.out.println("The default values of primitive data types

are:"); System.out.println("Byte :"+b);

System.out.println("Short :"+s);
System.out.println("Int :"+i);

System.out.println("Long :"+l);
System.out.println("Float :"+f);

System.out.println("Double :"+d);
System.out.println("Char :"+c);

System.out.println("Boolean :"+bl);
}

}
Output:
The default values of primitive data types are:
Byte :0
Short :0
Int :0
Long :0
Float :0.0
Double :0.0
Char :
Boolean :false

4. Java Program to Find ASCII Value of a character

public class AsciiValue {

public static void main(String[] args) {

char ch = 'a';
int ascii = ch;
// You can also cast char to int
int castAscii = (int) ch;

System.out.println("The ASCII value of " + ch + " is: " + ascii);

System.out.println("The ASCII value of " + ch + " is: " + castAscii);
}
}
Output

The ASCII value of a is: 97

The ASCII value of a is: 97

Java Program to Calculate Area of Rectangle

import java.util.Scanner;
class AreaOfRectangle {
public static void main (String[] args)
{
Scanner scanner = new Scanner(System.in);
System.out.println("Enter the length of Rectangle:");
double length = scanner.nextDouble();
 System.out.println("Enter the width of Rectangle:");
double width = scanner.nextDouble();
//Area = length*width;
double area = length*width;
System.out.println("Area of Rectangle is:"+area);
}
}
Output: Enter the length of Rectangle:
2
Enter the width of Rectangle:
8
Area of Rectangle is:16.0

5. Java Program to Compute Quotient and Remainder

public class QuotientRemainder {

public static void main(String[] args) {

int dividend = 25, divisor = 4;

int quotient = dividend / divisor;

int remainder = dividend % divisor;

System.out.println("Quotient = " + quotient);

System.out.println("Remainder = " + remainder);
}
}
Output:

Quotient = 6
Remainder = 1

6. Java Program to Swap Two Numbers

public class SwapNumbers {

 public static void main(String[] args) {

float first = 1.20f, second = 2.45f;

System.out.println("--Before swap--");
System.out.println("First number = " + first);
System.out.println("Second number = " + second);

// Value of first is assigned to temporary

float temporary = first;

// Value of second is assigned to first

first = second;

// Value of temporary (which contains the initial value of first) is assigned to second
second = temporary;

System.out.println("--After swap--");
System.out.println("First number = " + first);
System.out.println("Second number = " + second);
}
}
Output:

--Before swap--
First number = 1.2
Second number = 2.45
--After swap--
First number = 2.45
Second number = 1.2

7. Check whether a number is even or odd

import java.util.Scanner;

public class EvenOdd {

public static void main(String[] args) {

Scanner reader = new Scanner(System.in);

System.out.print("Enter a number: ");

int num = reader.nextInt();

if(num % 2 == 0)
System.out.println(num + " is even");
 else
System.out.println(num + " is odd");
}
}
Output

Enter a number: 12
12 is even

8. Java Program to Check Whether an Alphabet is Vowel or Consonant

public class VowelConsonant {

public static void main(String[] args) {

char ch = 'i';

if(ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u' )

System.out.println(ch + " is vowel");
else
System.out.println(ch + " is consonant");

}
}
Output

i is vowel

9. Find Largest Among three numbers using if..else statement

public class Largest {

public static void main(String[] args) {

double n1 = -4.5, n2 = 3.9, n3 = 2.5;

if( n1 >= n2 && n1 >= n3)

System.out.println(n1 + " is the largest number.");

else if (n2 >= n1 && n2 >= n3)

System.out.println(n2 + " is the largest number.");

else
System.out.println(n3 + " is the largest number.");
}
}
Output
3.9 is the largest number.

Java Program to demonstrate the program of grading system for fail, D grade, C grade, B
grade, A grade and A+.
public class IfElseIfExample {
public static void main(String[] args) {
int marks=65;

if(marks<50){
System.out.println("fail");
}
else if(marks>=50 && marks<60){
System.out.println("D grade");
}
else if(marks>=60 && marks<70){
System.out.println("C grade");
}
else if(marks>=70 && marks<80){
System.out.println("B grade");
}
else if(marks>=80 && marks<90){
System.out.println("A grade");
}else if(marks>=90 && marks<100){
System.out.println("A+ grade");
}else{
System.out.println("Invalid!");
}
}
}

Output:C grade

10. Java Program to Find Roots of a Quadratic Equation

public class Main {

public static void main(String[] args) {

// value a, b, and c
double a = 2.3, b = 4, c = 5.6;
double root1, root2;

// calculate the determinant (b2 - 4ac)

double determinant = b * b - 4 * a * c;

// check if determinant is greater than 0

if (determinant > 0) {

// two real and distinct roots

root1 = (-b + Math.sqrt(determinant)) / (2 * a);
root2 = (-b - Math.sqrt(determinant)) / (2 * a);

System.out.format("root1 = %.2f and root2 = %.2f", root1, root2);

}

// check if determinant is equal to 0

else if (determinant == 0) {

// two real and equal roots

// determinant is equal to 0
// so -b + 0 == -b
root1 = root2 = -b / (2 * a);
System.out.format("root1 = root2 = %.2f;", root1);
}

// if determinant is less than zero

else {

// roots are complex number and distinct

double real = -b / (2 * a);
double imaginary = Math.sqrt(-determinant) / (2 * a);
 System.out.format("root1 = %.2f+%.2fi", real, imaginary);
System.out.format("\nroot2 = %.2f-%.2fi", real, imaginary);
}
}
}
Output

root1 = -0.87+1.30i and root2 = -0.87-1.30i

11. Java Program to Check a Leap Year

public class Main {

public static void main(String[] args) {

// year to be checked
int year = 1996;
boolean leap = false;

// if the year is divided by 4

if (year % 4 == 0) {

// if the year is century

if (year % 100 == 0) {

// if year is divided by 400

// then it is a leap year
if (year % 400 == 0)
leap = true;
else
leap = false;
}

// if the year is not century

else
leap = true;
}

else
leap = false;

if (leap)
System.out.println(year + " is a leap year.");
else
System.out.println(year + " is not a leap year.");
}
}
Output
1900 is not a leap year.

12. Check if a Number is Positive or Negative using if else

public class PositiveNegative {

public static void main(String[] args) {

double number = 12.3;

// true if number is less than 0

if (number < 0.0)
System.out.println(number + " is a negative number.");

// true if number is greater than 0

else if ( number > 0.0)
System.out.println(number + " is a positive number.");

// if both test expression is evaluated to false

else
System.out.println(number + " is 0.");
}
}
Output

12.3 is a positive number.

13. Java Program to Check Alphabet using if else

public class Alphabet {

public static void main(String[] args) {

char c = '*';

if( (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
System.out.println(c + " is an alphabet.");
else
System.out.println(c + " is not an alphabet.");
}
}
Output

* is not an alphabet.

14. Sum of Natural Numbers using for loop

public class SumNatural {

public static void main(String[] args) {

int num = 100, sum = 0;

for(int i = 1; i <= num; ++i)

{
// sum = sum + i;
sum += i;
}

System.out.println("Sum = " + sum);

}
}
Output

Sum = 5050

15. Find Factorial of a number

public class Factorial {

public static void main(String[] args) {

int num = 10;

long factorial = 1;
for(int i = 1; i <= num; ++i)
{
// factorial = factorial * i;
factorial *= i;
}
System.out.printf("Factorial of %d = %d", num, factorial);
}
}
Output

Factorial of 10 = 3628800

16. Generate Multiplication Table using for loop

public class MultiplicationTable {

public static void main(String[] args) {

int num = 5;
for(int i = 1; i <= 10; ++i)
 {
System.out.printf("%d * %d = %d \n", num, i, num * i);
}
}
}
Output

5*1=5
5 * 2 = 10
5 * 3 = 15
5 * 4 = 20
5 * 5 = 25
5 * 6 = 30
5 * 7 = 35
5 * 8 = 40
5 * 9 = 45
5 * 10 = 50

17. Display Fibonacci Series Using for Loop

class Main {
public static void main(String[] args) {

int n = 10, firstTerm = 0, secondTerm = 1;

System.out.println("Fibonacci Series till " + n + " terms:");

for (int i = 1; i <= n; ++i) {

System.out.print(firstTerm + ", ");

// compute the next term

int nextTerm = firstTerm + secondTerm;
firstTerm = secondTerm;
secondTerm = nextTerm;
}
}
}
Output

Fibonacci Series till 10 terms:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34,

18. Display uppercased alphabet using for loop

class Main {
public static void main(String[] args) {

char c;
 for(c = 'A'; c <= 'Z'; ++c)
System.out.print(c + " ");
}
}
Output

ABCDEFGHIJKLMNOPQRSTUVWXYZ

19. Count Number of Digits in an Integer using while loop

public class Main {

public static void main(String[] args) {

int count = 0, num = 0003452;

while (num != 0) {
// num = num/10
num /= 10;
++count;
}

System.out.println("Number of digits: " + count);

}
}
Output

Number of digits: 4

20. Reverse a Number using a while loop in Java

class Main {
public static void main(String[] args) {

int num = 1234, reversed = 0;

System.out.println("Original Number: " + num);

// run loop until num becomes 0

while(num != 0) {

// get last digit from num

int digit = num % 10;
reversed = reversed * 10 + digit;

// remove the last digit from num

num /= 10;
}
 System.out.println("Reversed Number: " + reversed);
}
}
Output

Reversed Number: 4321

21. Calculate power of a number using a while loop

class Main {
public static void main(String[] args) {

int base = 3, exponent = 4;

long result = 1;

while (exponent != 0) {
result *= base;
--exponent;
}

System.out.println("Answer = " + result);

}
}
Output

Answer = 81

22. Program to Check Prime Number using a for loop

public class Main {

public static void main(String[] args) {

int num = 29;

boolean flag = false;
for (int i = 2; i <= num / 2; ++i) {
// condition for nonprime number
if (num % i == 0) {
flag = true;
break;
}
}

if (!flag)
System.out.println(num + " is a prime number.");
else
 System.out.println(num + " is not a prime number.");
}
}
Output

29 is a prime number.

23. Check Armstrong Number for 3 digit number

public class Armstrong {

public static void main(String[] args) {

int number = 371, originalNumber, remainder, result = 0;

originalNumber = number;

while (originalNumber != 0)
{
remainder = originalNumber % 10;
result += Math.pow(remainder, 3);
originalNumber /= 10;
}

if(result == number)
System.out.println(number + " is an Armstrong number.");
else
System.out.println(number + " is not an Armstrong number.");
}
}
Output

371 is an Armstrong number.

24. Factors of a Positive Integer

public class Main {

public static void main(String[] args) {

// positive number
int number = 60;

System.out.print("Factors of " + number + " are: ");

// loop runs from 1 to 60

for (int i = 1; i <= number; ++i) {
 // if number is divided by i
// i is the factor
if (number % i == 0) {
System.out.print(i + " ");
}
}
}
}
Output

Factors of 60 are: 1 2 3 4 5 6 10 12 15 20 30 60

25. Simple Calculator using Java switch Statement

import java.util.Scanner;

class Main {
public static void main(String[] args) {

char operator;
Double number1, number2, result;

// create an object of Scanner class

Scanner input = new Scanner(System.in);

// ask users to enter operator

System.out.println("Choose an operator: +, -, *, or /");
operator = input.next().charAt(0);

// ask users to enter numbers

System.out.println("Enter first number");
number1 = input.nextDouble();

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

number2 = input.nextDouble();

switch (operator) {

// performs addition between numbers

case '+':
result = number1 + number2;
System.out.println(number1 + " + " + number2 + " = " + result);
break;

// performs subtraction between numbers

case '-':
 result = number1 - number2;
System.out.println(number1 + " - " + number2 + " = " + result);
break;

// performs multiplication between numbers

case '*':
result = number1 * number2;
System.out.println(number1 + " * " + number2 + " = " + result);
break;

// performs division between numbers

case '/':
result = number1 / number2;
System.out.println(number1 + " / " + number2 + " = " + result);
break;

default:
System.out.println("Invalid operator!");
break;
}

input.close();
}
}
Output 1

Choose an operator: +, -, *, or /
*
Enter first number
3
Enter second number
9
3.0 * 9.0 = 27.