Java Basic

Java Programming Examples

Hello World Program

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Hello, World!

Switch Case Example

int day = 1;
switch (day) {
    case 1:
        System.out.println("Sunday");
        break;
    case 2:
        System.out.println("Monday");
        break;
    default:
        System.out.println("Other Day");
}

Sunday

If-Else Example

int age = 20;
if (age >= 18) {
    System.out.println("You are an adult.");
} else {
    System.out.println("You are a minor.");
}

You are an adult.

For Loop Example

for (int i = 0; i < 5; i++) {
    System.out.println("Iteration " + (i + 1));
}

Iteration 1
Iteration 2
Iteration 3
Iteration 4
Iteration 5

While Loop Example

int count = 0;
while (count < 3) {
    System.out.println("Count: " + count);
    count++;
}

Count: 0
Count: 1
Count: 2

Break and Continue Example

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        continue;
    }
    if (i == 4) {
        break;
    }
    System.out.println("Value: " + i);
}

Value: 1
Value: 2

Prime Number Check

public class PrimeCheck {
    public static boolean isPrime(int num) {
        if (num <= 1)
            return false;
        for (int i = 2; i * i <= num; i++) {
            if (num % i == 0)
                return false;
        }
        return true;
    }

    public static void main(String[] args) {
        System.out.println(isPrime(17)); // true
        System.out.println(isPrime(25)); // false
    }
}

true
false

Fibonacci Series

public class Fibonacci {
    public static void main(String[] args) {
        int n = 7;
        int[] fib = new int[n];
        fib[0] = 0;
        fib[1] = 1;
        for (int i = 2; i < n; i++) {
            fib[i] = fib[i - 1] + fib[i - 2];
        }
        for (int i = 0; i < n; i++) {
            System.out.print(fib[i] + " ");
        }
    }
}

0 1 1 2 3 5 8

Palindrome Number Check

public class PalindromeCheck {
    public static boolean isPalindrome(int num) {
        int original = num;
        int reversed = 0;
        while (num > 0) {
            int digit = num % 10;
            reversed = reversed * 10 + digit;
            num /= 10;
        }
        return original == reversed;
    }

    public static void main(String[] args) {
        System.out.println(isPalindrome(121)); // true
        System.out.println(isPalindrome(123)); // false
    }
}

true
false