Simple 27 Java Program on basic java syntax

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1. Area of Rectangle:
import java.util.Scanner;
public class RectangleArea {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.print("Enter the length of the rectangle: ");
double length = sc.nextDouble();
System.out.print("Enter the width of the rectangle: ");
double width = sc.nextDouble();
// Calculate the area of the rectangle
double area = length * width;
System.out.println("The area of the rectangle is: " + area);
sc.close();
}
}
2. Addition of Two Numbers.
public class Sum
{
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter First Number");
int a=sc.nextInt();
System.out.println("Enter Second Number");
int b=sc.nextInt();
int sum=a+b;
System.out.println("Addition is"+sum);
}
}
3. Factorial of Number
public class SimpleFactorial
{
{
System.out.print("Enter a number to calculate its factorial: ");
int number = sc.nextInt();
// Calculate the factorial
int factorial = 1;
for (int i = 1; i <= number; i++)
{
factorial *= i;
//factorial=factorial*i;
}
System.out.println("The factorial is: " + factorial);
sc.close();
}

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}
4. Even or Odd
public class EvenOddChecker {
System.out.print("Enter a number: ");
// Check if the number is even or odd
if (number % 2 == 0) {
System.out.println(number + " is even.");
} else {
System.out.println(number + " is odd.");
}
sc.close();
}
}
5. Fibonacci Series:
public class Fibonacci {
System.out.print("Enter the number of terms: ");
int n = sc.nextInt();
int a = 0, b = 1;
System.out.print("Fibonacci Series: " + a + ", " + b);
for (int i = 2; i < n; i++) {
int next = a + b;
System.out.print(", " + next);
a = b;
b = next;
}
}
}
6. Reverse the number:
class Main {
Scanner sc=new Scanner(System.in);
System.out.println("Enter the number to reverse:");
int num = sc.nextInt();
int 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;

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}
System.out.println("Reversed Number: " + reversed);
}
}
7. Armstrong or not:
public class ArmstrongNumber {
int originalNumber = number;
int result = 0;
int n = 0;
// Count the number of digits
while (originalNumber != 0) {
originalNumber /= 10;
++n;
}
originalNumber = number;
// Calculate the sum of the nth power of its digits
while (originalNumber != 0) {
int digit = originalNumber % 10;
result += Math.pow(digit, n);
originalNumber /= 10;
}
if (result == number) {
System.out.println(number + " is an Armstrong number.");
} else {
System.out.println(number + " is not an Armstrong number.");
}
}
}
8. Prime or Not:
public class PrimeCheck {
boolean isPrime = true;
for (int i = 2; i <= number / 2; i++) {
if (number % i == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
System.out.println(number + " is a prime number.");
} else {
System.out.println(number + " is not a prime number.");
}
}
}

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9. Simple Calculator:
public class Calculator {
System.out.print("Enter first number: ");
double num1 = sc.nextDouble();
System.out.print("Enter second number: ");
double num2 = sc.nextDouble();
System.out.print("Enter an operator (+, -, *, /): ");
char operator = sc.next().charAt(0);
double result;
switch (operator) {
case '+':
result = num1 + num2;
System.out.println("Addition is: " +result);
break;
case '-':
result = num1 - num2;
System.out.println("Subtraction is: " +result);
break;
case '*':
result = num1 * num2;
System.out.println("Multiplication is: " +result);
break;
case '/':
result = num1 / num2;
System.out.println("Devision is: " +result);
break;
default:
System.out.println("Invalid operator!");
return;
}
// System.out.println("Result: " + result);
}
}
10. Swap two Number:
public class SwapNumbers {
System.out.print("Enter the first number: ");
int num1 = sc.nextInt();
System.out.print("Enter the second number: ");
int num2 = sc.nextInt();
// Display numbers before swapping
System.out.println("Before swapping: ");
System.out.println("First number = " + num1);
System.out.println("Second number = " + num2);
// Swap the numbers
int temp = num1;
num1 = num2;
num2 = temp;
// Display numbers after swapping

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System.out.println("After swapping: ");
System.out.println("First number = " + num1);
System.out.println("Second number = " + num2);
sc.close();
}
}
11. Pyramid Pattern of Star
public class PyramidPattern
{
public static void main(String args[])
{
int i, j, row = 6;
for (i=0; i<row; i++)
{
for (j=row-i; j>1; j--)
{
System.out.print(" ");
}
for (j=0; j<=i; j++ )
{
System.out.print("* ");
}
System.out.println();
} } }
12. Pattern Program:
public class Pattern1
{
public static void main(String args[])
{
int i, j,number, n=7;
for(i=0; i<n; i++)
{
number=1;
for(j=0; j<=i; j++)
{
System.out.print(number+ " ");

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number++;
}
} } }
{
{
int i, j, k = 1;
for (i = 1; i <= 7; i++)
{
for (j = 1; j< i + 1; j++)
{
System.out.print(k++ + " ");
}
} } }
import java.util.*;
{
{
int i, j, rows;
System.out.print("Enter the number of rows you want to print: ");
rows = sc.nextInt();
for (i = 1; i <= rows; i++)

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{
for (j = 1; j <= i; j++)
{
System.out.print(i+" ");
}
} }}
public class RightAlphabaticPattern
{
{
int alphabet = 65; //ASCII value of capital A is 65
for (int i = 0; i <= 8; i++)
{
for (int j = 0; j <= i; j++)
{
System.out.print((char) (alphabet + j) + " ");
}
}}}
16. Array program
Find the Sum of Array Elements
public class Main {
// Declare and initialize an array of 5 integers
int[] array = {10, 20, 30, 40, 50};
// Calculate the sum of the elements of the array
int sum = 0;
for (int i = 0; i < array.length; i++) {
sum += array[i];
}
// Print the sum of the elements
System.out.println("Sum of the array elements is: " + sum);
}

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}
Output
Sum of the array elements is: 150
17. Find the Maximum Element in an Array
public class Main {
// Declare and initialize an array of 5 integers
int[] array = {10, 20, 30, 40, 50};
// Find the maximum element in the array
int max = array[0];
if (array[i] > max) {
max = array[i];
}
}
// Print the maximum element
System.out.println("Maximum element in the array is: " + max);
}
}
Output
Maximum element in the array is: 50
X-X-X-X-X-X-X-X-X-X-X
18. Sum of All Elements in a 2D Array
public class Main {
// Declare and initialize a 2D array
int[][] array = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};
// Calculate the sum of all elements in the 2D array
int sum = 0;
for (int j = 0; j < array[i].length; j++) {
sum += array[i][j];
}
}
System.out.println("Sum of all elements in the 2D array is: " + sum);
}
}
Output
Sum of all elements in the 2D array is: 45

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19. Transpose of a 2D Array
public class Main {
// Declare and initialize a 2D array
int[][] array = {
{1, 2, 3},
{4, 5, 6},
{7, 8, 9}
};
// Transpose the 2D array
int[][] transpose = new int[array[0].length][array.length];
for (int j = 0; j < array[i].length; j++) {
transpose[j][i] = array[i][j];
}
}
// Print the transposed array
System.out.println("Transpose of the 2D array is:");
for (int i = 0; i < transpose.length; i++) {
for (int j = 0; j < transpose[i].length; j++) {
System.out.print(transpose[i][j] + " ");
}
}
}
}
Output
Transpose of the 2D array is:
1 4 7
2 5 8
3 6 9
20. Multiplication of Two 2D Arrays
public class Main {
// Declare and initialize two 2D arrays
int[][] array1 = {
{1, 2, 3},
{4, 5, 6}
};
int[][] array2 = {
{7, 8},
{9, 10},
{11, 12}
};
// Multiply the two 2D arrays
int[][] product = new int[array1.length][array2[0].length];
for (int i = 0; i < array1.length; i++) {
for (int j = 0; j < array2[0].length; j++) {

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for (int k = 0; k < array1[0].length; k++) {
product[i][j] += array1[i][k] * array2[k][j];
}
}
}
// Print the product of the two arrays
System.out.println("Product of the two 2D arrays is:");
for (int i = 0; i < product.length; i++) {
for (int j = 0; j < product[i].length; j++) {
System.out.print(product[i][j] + " ");
}
}
}
}
Output
Product of the two 2D arrays is:
58 64
139 154
21. Java Program To print Day of Week.
22.
public class DayOfWeek {
// Prompt user for input
System.out.print("Enter a number (1-7) for the day of the week: ");
int day = sc.nextInt();
// Determine the day of the week using switch case
String dayName;
switch (day) {
case 1:
dayName = "Monday";
break;
case 2:
dayName = "Tuesday";
break;
case 3:
dayName = "Wednesday";
break;
case 4:
dayName = "Thursday";
break;
case 5:
dayName = "Friday";
break;
case 6:
dayName = "Saturday";
break;
case 7:

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dayName = "Sunday";
break;
default:
dayName = "Invalid input! Please enter a number between 1 and 7.";
}
// Output the result
System.out.println("The day of the week is: " + dayName);
// Close the scanner
sc.close();
}
}
23. Write a Java program that checks whether a given character is a vowel or
consonant using a switch statement.
public class VowelOrConsonant {
System.out.print("Enter a letter: ");
char letter = sc.next().toLowerCase().charAt(0);
switch (letter) {
case 'a':
case 'e':
case 'i':
case 'o':
case 'u':
System.out.println(letter + " is a vowel.");
break;
default:
if (Character.isLetter(letter)) {
System.out.println(letter + " is a consonant.");
} else {
System.out.println("Invalid input, not a letter.");
}
}
sc.close();
}
}
24. Write a Java program to determine a student's grade based on marks using a
switch statement. The program should output a grade based on ranges of
marks.
public class GradeCalculator {
System.out.print("Enter your marks (0-100): ");
int marks = sc.nextInt();
char grade;
switch (marks / 10)
{
case 10:
case 9:
grade = 'A';

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break;
case 8:
grade = 'B';
break;
case 7:
grade = 'C';
break;
case 6:
grade = 'D';
break;
case 5:
grade = 'E';
break;
default:
grade = 'F';
}
System.out.println("Your grade is: " + grade);
sc.close();
}
}
25. Write a Java program that takes a number between 1 and 12 from the user
and prints the corresponding month name using a switch statement.
public class MonthFinder {
System.out.print("Enter month number (1-12): ");
int month = scanner.nextInt();
String monthName;
switch (month) {
case 1:
monthName = "January";
break;
case 2:
monthName = "February";
break;
case 3:
monthName = "March";
break;
case 4:
monthName = "April";
break;
case 5:
monthName = "May";
break;
case 6:
monthName = "June";
break;
case 7:
monthName = "July";
break;
case 8:
monthName = "August";
break;

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case 9:
monthName = "September";
break;
case 10:
monthName = "October";
break;
case 11:
monthName = "November";
break;
case 12:
monthName = "December";
break;
default:
monthName = "Invalid month number!";
}
System.out.println("The month is: " + monthName);
sc.close();
}
}
26. Write a Java program that calculates the sum of natural numbers from 1 to a
user-defined value using a while loop.
public class SumOfNum {
System.out.print("Enter the upper limit: ");
int n = sc.nextInt();
int sum = 0;
int i = 1;
while (i <= n) {
sum += i; // add current number to sum
i++; // increment the counter
}
System.out.println("Sum of natural numbers from 1 to " + n + " is: " + sum);
sc.close();
}
}
27. Write a Java program that reverses a given number using a while loop.
public class ReverseNumber {
int reverse = 0;
while (number != 0) {
int digit = number % 10;
reverse = reverse * 10 + digit;
number /= 10;
}
System.out.println("Reversed number: " + reverse);
sc.close();
}
}

Simple 27 Java Program on basic java syntax

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