Write a program to reverse a string without using any built-in functions.
public class ReverseString {
public static void main(String[] args) {
String inputStr = "Hello, World!";
String reversedStr = reverseString(inputStr);
System.out.println("Reversed String: " + reversedStr);
}
public static String reverseString(String s) {
String reversed = "";
for (int i = s.length() - 1; i >= 0; i--) {
reversed += s.charAt(i);
}
return reversed;
}
}
Write a program to find the factorial of a number using recursion.
public class Factorial {
public static void main(String[] args) {
int num = 5;
int result = factorial(num);
System.out.println("Factorial of " + num + " is " + result);
}
public static int factorial(int n) {
if (n == 0) {
return 1;
} else {
return n * factorial(n - 1);
}
}
}
Write a program to check whether a given string is a palindrome.
public class Palindrome {
public static void main(String[] args) {
String input = "madam";
if (isPalindrome(input)) {
System.out.println(input + " is a palindrome.");
} else {
System.out.println(input + " is not a palindrome.");
}
}
public static boolean isPalindrome(String s) {
String reversed = "";
for (int i = s.length() - 1; i >= 0; i--) {
reversed += s.charAt(i);
}
return s.equals(reversed);
}
}
Write a program to find all prime numbers between 1 and N.
public class PrimeNumbers {
public static void main(String[] args) {
int range = 50;
System.out.println("Prime numbers between 1 and " + range + ":");
for (int i = 2; i <= range; i++) {
if (isPrime(i)) {
System.out.print(i + " ");
}
}
}
public static boolean isPrime(int n) {
if (n <= 1) {
return false;
}
for (int i = 2; i <= Math.sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
}
Write a program to print the Fibonacci series up to a given number of terms.
public class Fibonacci {
public static void main(String[] args) {
int n = 10; // Number of terms
System.out.println("Fibonacci series up to " + n + " terms:");
for (int i = 0; i < n; i++) {
System.out.print(fibonacci(i) + " ");
}
}
public static int fibonacci(int n) {
if (n <= 1) {
return n;
} else {
return fibonacci(n - 1) + fibonacci(n - 2);
}
}
}
Write a program to calculate the sum of digits of a given number.
public class SumOfDigits {
public static void main(String[] args) {
int number = 12345;
int sum = sumOfDigits(number);
System.out.println("Sum of digits of " + number + " is " + sum);
}
public static int sumOfDigits(int n) {
int sum = 0;
while (n != 0) {
sum += n % 10;
n /= 10;
}
return sum;
}
}
Write a program to count the number of vowels and consonants in a given string.
public class VowelConsonantCount {
public static void main(String[] args) {
String input = "Hello World";
int vowels = 0, consonants = 0;
for (int i = 0; i < input.length(); i++) {
char ch = input.charAt(i);
if (Character.isLetter(ch)) {
if (isVowel(ch)) {
vowels++;
} else {
consonants++;
}
}
}
System.out.println("Vowels: " + vowels);
System.out.println("Consonants: " + consonants);
}
public static boolean isVowel(char c) {
c = Character.toLowerCase(c);
return (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u');
}
}
Write a program to count the number of words in a given string.
public class WordCount {
public static void main(String[] args) {
String input = "This is a sample sentence.";
int wordCount = countWords(input);
System.out.println("Number of words: " + wordCount);
}
public static int countWords(String str) {
String[] words = str.split("\\s+");
return words.length;
}
}
Write a program to print the multiplication table for a given number.
import java.util.Scanner;
public class MultiplicationTable {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int num = scanner.nextInt();
printTable(num);
}
public static void printTable(int num) {
for (int i = 1; i <= 10; i++) {
System.out.println(num + " * " + i + " = " + (num * i));
}
}
}
Write a program to find the largest number among three numbers.
import java.util.Scanner;
public class LargestNumber {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter three numbers: ");
int num1 = scanner.nextInt();
int num2 = scanner.nextInt();
int num3 = scanner.nextInt();
int largest = findLargest(num1, num2, num3);
System.out.println("The largest number is: " + largest);
}
public static int findLargest(int num1, int num2, int num3) {
return Math.max(num1, Math.max(num2, num3));
}
}
Write a program to check if a given number is prime or not.
import java.util.Scanner;
public class PrimeNumber {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int num = scanner.nextInt();
if (isPrime(num)) {
System.out.println(num + " is a prime number.");
} else {
System.out.println(num + " is not a prime number.");
}
}
public static boolean isPrime(int num) {
if (num <= 1) {
return false;
}
for (int i = 2; i <= Math.sqrt(num); i++) {
if (num % i == 0) {
return false;
}
}
return true;
}
}
Write a program to find the sum of elements in an array.
public class ArraySum {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
int sum = sumOfArray(arr);
System.out.println("Sum of elements in the array: " + sum);
}
public static int sumOfArray(int[] arr) {
int sum = 0;
for (int num : arr) {
sum += num;
}
return sum;
}
}
Write a program to print the Fibonacci sequence up to n numbers using iteratio
import java.util.Scanner;
public class FibonacciIterative {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter the number of terms: ");
int n = scanner.nextInt();
printFibonacci(n);
}
public static void printFibonacci(int n) {
int first = 0, second = 1;
System.out.print("Fibonacci Sequence: ");
for (int i = 0; i < n; i++) {
System.out.print(first + " ");
int next = first + second;
first = second;
second = next;
}
}
}
Write a program to add two matrices of the same dimensions.
public class MatrixSum {
public static void main(String[] args) {
int[][] matrix1 = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
int[][] matrix2 = {{9, 8, 7}, {6, 5, 4}, {3, 2, 1}};
int[][] result = addMatrices(matrix1, matrix2);
System.out.println("Sum of the matrices:");
printMatrix(result);
}
public static int[][] addMatrices(int[][] matrix1, int[][] matrix2) {
int rows = matrix1.length;
int cols = matrix1[0].length;
int[][] sum = new int[rows][cols];
for (int i = 0; i < rows; i++) {
for (int j = 0; j < cols; j++) {
sum[i][j] = matrix1[i][j] + matrix2[i][j];
}
}
return sum;
}
public static void printMatrix(int[][] matrix) {
for (int[] row : matrix) {
for (int num : row) {
System.out.print(num + " ");
}
System.out.println();
}
}
}
Write a program to find the GCD of two numbers.
import java.util.Scanner;
public class GCD {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter two numbers: ");
int num1 = scanner.nextInt();
int num2 = scanner.nextInt();
int gcd = findGCD(num1, num2);
System.out.println("GCD of " + num1 + " and " + num2 + " is " + gcd);
}
public static int findGCD(int num1, int num2) {
while (num2 != 0) {
int temp = num2;
num2 = num1 % num2;
num1 = temp;
}
return num1;
}
}