Simple Java Programs

Java, a flexible and extensively used programming language, serves various domains. For Java beginners, here are five straightforward simple programs that introduce essential concepts and ensure a seamless initiation into the language.

1. Even or Odd Checker:

This program determines whether a given number is even or odd.

import java.util.Scanner;

public class EvenOrOdd {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

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

int num = scanner.nextInt();

if (num % 2 == 0) {

System.out.println(num + " is an even number.");

} else {

System.out.println(num + " is an odd number.");

}

scanner.close();

}

Output:

Enter a number: 7

7 is an odd number.

2. Celsius to Fahrenheit Converter:

This program converts temperature from Celsius to Fahrenheit.

import java.util.Scanner;

public class CelsiusToFahrenheit {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

System.out.print("Enter temperature in Celsius: ");

double celsius = scanner.nextDouble();

double fahrenheit = (celsius * 9/5) + 32;

System.out.println("Temperature in Fahrenheit: " + fahrenheit);

scanner.close();

}

Output:

Enter temperature in Celsius: 25

Temperature in Fahrenheit: 77.0

3. Palindrome Checker:

This program checks if a given word is a palindrome (reads the same forwards and backwards).

import java.util.Scanner;

public class PalindromeChecker {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

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

String word = scanner.nextLine();

String reversedWord = new StringBuilder(word).reverse().toString();

if (word.equalsIgnoreCase(reversedWord)) {

System.out.println("It's a palindrome!");

} else {

System.out.println("It's not a palindrome.");

}

scanner.close();

}

Output:

Enter a word: radar

It's a palindrome!

4. Sum of Natural Numbers:

This program calculates the sum of natural numbers up to a given number.

import java.util.Scanner;

public class SumOfNaturalNumbers {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

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

int num = scanner.nextInt();

int sum = 0;

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

sum += i;

}

System.out.println("Sum of natural numbers up to " + num + " is: " + sum);

scanner.close();

}

Output:

Enter a number: 5

Sum of natural numbers up to 5 is: 15

5. Factorial of a Number (Recursive):

This program calculates the factorial of a given number using a recursive function.

import java.util.Scanner;

public class RecursiveFactorial {

public static void main(String[] args) {

Scanner scanner = new Scanner(System.in);

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

int num = scanner.nextInt();

int factorial = calculateFactorial(num);

System.out.println("Factorial of " + num + " is: " + factorial);

scanner.close();

}

public static int calculateFactorial(int n) {

if (n == 0 || n == 1) {

return 1;

} else {

return n * calculateFactorial(n - 1);

}

Output:

Enter a number: 4

Factorial of 4 is: 24