In this article we give you 25 simple Java code examples that cover various programming concepts like control structures, loops, arrays, methods, and object-oriented programming.
We always find that actually trying out code examples and running them is one of the best ways to learn a new language
Table of Contents
1. Hello World
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
2. Sum of Two Numbers
public class Sum {
public static void main(String[] args) {
int a = 5, b = 10;
int sum = a + b;
System.out.println("Sum: " + sum);
}
}
3. Check Even or Odd
public class EvenOdd {
public static void main(String[] args) {
int num = 10;
if (num % 2 == 0) {
System.out.println(num + " is even");
} else {
System.out.println(num + " is odd");
}
}
}
4. Find Largest Number
public class LargestNumber {
public static void main(String[] args) {
int a = 5, b = 10, c = 3;
if (a > b && a > c) {
System.out.println("Largest is: " + a);
} else if (b > c) {
System.out.println("Largest is: " + b);
} else {
System.out.println("Largest is: " + c);
}
}
}
5. Factorial of a Number
public class Factorial {
public static void main(String[] args) {
int num = 5;
int fact = 1;
for (int i = 1; i <= num; i++) {
fact *= i;
}
System.out.println("Factorial: " + fact);
}
}
6. Fibonacci Series
public class Fibonacci {
public static void main(String[] args) {
int a = 0, b = 1, n = 10;
System.out.print(a + " " + b);
for (int i = 2; i < n; i++) {
int next = a + b;
System.out.print(" " + next);
a = b;
b = next;
}
}
}
7. Reverse a String
public class ReverseString {
public static void main(String[] args) {
String str = "Hello";
String rev = "";
for (int i = str.length() - 1; i >= 0; i--) {
rev += str.charAt(i);
}
System.out.println("Reversed: " + rev);
}
}
8. Prime Number Check
public class PrimeCheck {
public static void main(String[] args) {
int num = 29;
boolean isPrime = true;
for (int i = 2; i <= num / 2; i++) {
if (num % i == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
System.out.println(num + " is prime");
} else {
System.out.println(num + " is not prime");
}
}
}
9. Sum of Array Elements
public class SumArray {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
int sum = 0;
for (int num : arr) {
sum += num;
}
System.out.println("Sum: " + sum);
}
}
10. Swap Two Variables
public class Swap {
public static void main(String[] args) {
int a = 5, b = 10;
System.out.println("Before swap: a = " + a + ", b = " + b);
int temp = a;
a = b;
b = temp;
System.out.println("After swap: a = " + a + ", b = " + b);
}
}
11. Multiplication Table
public class MultiplicationTable {
public static void main(String[] args) {
int num = 5;
for (int i = 1; i <= 10; i++) {
System.out.println(num + " x " + i + " = " + num * i);
}
}
}
12. Armstrong Number
public class ArmstrongNumber {
public static void main(String[] args) {
int num = 153, sum = 0, temp = num;
while (temp != 0) {
int digit = temp % 10;
sum += Math.pow(digit, 3);
temp /= 10;
}
if (sum == num) {
System.out.println(num + " is an Armstrong number");
} else {
System.out.println(num + " is not an Armstrong number");
}
}
}
13. Sum of Digits
public class SumOfDigits {
public static void main(String[] args) {
int num = 1234, sum = 0;
while (num != 0) {
sum += num % 10;
num /= 10;
}
System.out.println("Sum of digits: " + sum);
}
}
14. Reverse a Number
public class ReverseNumber {
public static void main(String[] args) {
int num = 1234, reversed = 0;
while (num != 0) {
int digit = num % 10;
reversed = reversed * 10 + digit;
num /= 10;
}
System.out.println("Reversed: " + reversed);
}
}
15. GCD of Two Numbers
public class GCD {
public static void main(String[] args) {
int a = 54, b = 24;
while (b != 0) {
int temp = b;
b = a % b;
a = temp;
}
System.out.println("GCD: " + a);
}
}
16. LCM of Two Numbers
public class LCM {
public static void main(String[] args) {
int a = 54, b = 24, gcd = 1;
for (int i = 1; i <= a && i <= b; i++) {
if (a % i == 0 && b % i == 0) {
gcd = i;
}
}
int lcm = (a * b) / gcd;
System.out.println("LCM: " + lcm);
}
}
17. Leap Year Check
public class LeapYear {
public static void main(String[] args) {
int year = 2024;
if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0) {
System.out.println(year + " is a leap year");
} else {
System.out.println(year + " is not a leap year");
}
}
}
18. Count Vowels in a String
public class VowelCount {
public static void main(String[] args) {
String str = "Hello World";
int count = 0;
for (char c : str.toCharArray()) {
if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
count++;
}
}
System.out.println("Vowel count: " + count);
}
}
19. Find Length of a String
public class StringLength {
public static void main(String[] args) {
String str = "Hello World";
System.out.println("Length: " + str.length());
}
}
20. Convert Binary to Decimal
public class BinaryToDecimal {
public static void main(String[] args) {
String binary = "1010";
int decimal = Integer.parseInt(binary, 2);
System.out.println("Decimal: " + decimal);
}
}
21. Convert Decimal to Binary
public class DecimalToBinary {
public static void main(String[] args) {
int decimal = 10;
String binary = Integer.toBinaryString(decimal);
System.out.println("Binary: " + binary);
}
}
22. Find ASCII Value of a Character
public class ASCIIValue {
public static void main(String[] args) {
char c = 'A';
int ascii = (int) c;
System.out.println("ASCII value: " + ascii);
}
}
23. Print Numbers from 1 to 10
public class PrintNumbers {
public static void main(String[] args) {
for (int i = 1; i <= 10; i++) {
System.out.println(i);
}
}
}
24. Find Minimum and Maximum in an Array
public class MinMaxArray {
public static void main(String[] args) {
int[] arr = {1, 2, 3, 4, 5};
int min = arr[0], max = arr[0];
for (int num : arr) {
if (num < min) { min = num; } if (num > max) {
max = num;
}
}
System.out.println("Min: " + min + ", Max: " + max);
}
}
25. Check if a Number is Palindrome
public class Palindrome {
public static void main(String[] args) {
int num = 121, reversed = 0, original = num;
while (num != 0) {
int digit = num % 10;
reversed = reversed * 10 + digit;
num /= 10;
}
if (original == reversed) {
System.out.println(original + " is a palindrome");
} else {
System.out.println(original + " is not a palindrome");
}
}
}