Here are 40 Java Basic Programs which you can practice to get knowledge :
- Hello World
Title: Print “Hello, World!”
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
Output:
Hello, World!
- Sum of Two Numbers
Title: Add Two Numbers
public class AddNumbers {
public static void main(String[] args) {
int num1 = 5;
int num2 = 10;
int sum = num1 + num2;
System.out.println("Sum: " + sum);
}
}
Output:
Sum: 15
- Find the Maximum Number
Title: Maximum Number
public class MaximumNumber {
public static void main(String[] args) {
int num1 = 5;
int num2 = 10;
int max = num1 > num2 ? num1 : num2;
System.out.println("Maximum number: " + max);
}
}
Output:
Maximum number: 10
- Check Even or Odd
Title: Even or Odd
public class EvenOrOdd {
public static void main(String[] args) {
int num = 7;
if (num % 2 == 0) {
System.out.println(num + " is even.");
} else {
System.out.println(num + " is odd.");
}
}
}
Output:
7 is odd.
- Calculate Factorial
Title: Factorial Calculation
public class Factorial {
public static void main(String[] args) {
int num = 5;
int factorial = 1;
for (int i = 1; i <= num; i++) {
factorial *= i;
}
System.out.println("Factorial of " + num + ": " + factorial);
}
}
Output:
Factorial of 5: 120
- Generate Fibonacci Series
Title: Fibonacci Series
public class Fibonacci {
public static void main(String[] args) {
int count = 10;
int num1 = 0, num2 = 1;
System.out.print("Fibonacci Series: " + num1 + ", " + num2);
for (int i = 2; i < count; i++) {
int sum = num1 + num2;
System.out.print(", " + sum);
num1 = num2;
num2 = sum;
}
System.out.println();
}
}
Output:
Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34
- Check Prime Number
Title: Prime Number
public class PrimeNumber {
public static void main(String[] args) {
int num = 13;
boolean isPrime = true;
if (num <= 1) {
isPrime = false;
} else {
for (int i = 2; i <= Math.sqrt(num); i++) {
if (num % i == 0) {
isPrime = false;
break;
}
}
}
if (isPrime) {
System.out.println(num + " is a prime
number.");
} else {
System.out.println(num + " is not a prime number.");
}
}
}
Output:
13 is a prime number.
- Reverse a Number
Title: Reverse Number
public class ReverseNumber {
public static void main(String[] args) {
int num = 12345;
int reversed = 0;
while (num != 0) {
int digit = num % 10;
reversed = reversed * 10 + digit;
num /= 10;
}
System.out.println("Reversed number: " + reversed);
}
}
Output:
Reversed number: 54321
- Calculate Area of a Circle
Title: Area of a Circle
public class CircleArea {
public static void main(String[] args) {
double radius = 5.0;
double area = Math.PI * radius * radius;
System.out.println("Area of the circle: " + area);
}
}
Output:
Area of the circle: 78.53981633974483
- Swap Two Numbers
Title: Swap Numbers
public class SwapNumbers {
public static void main(String[] args) {
int num1 = 10;
int num2 = 20;
System.out.println("Before swapping: num1 = " + num1 + ", num2 = " + num2);
int temp = num1;
num1 = num2;
num2 = temp;
System.out.println("After swapping: num1 = " + num1 + ", num2 = " + num2);
}
}
Output:
Before swapping: num1 = 10, num2 = 20 After swapping: num1 = 20, num2 = 10
- Check Leap Year
Title: Leap Year
public class LeapYear {
public static void main(String[] args) {
int year = 2020;
boolean isLeapYear = false;
if (year % 4 == 0) {
if (year % 100 == 0) {
if (year % 400 == 0) {
isLeapYear = true;
}
} else {
isLeapYear = true;
}
}
if (isLeapYear) {
System.out.println(year + " is a leap year.");
} else {
System.out.println(year + " is not a leap year.");
}
}
}
Output:
2020 is a leap year.
- Calculate Power of a Number
Title: Power Calculation
public class Power {
public static void main(String[] args) {
int base = 2;
int exponent = 5;
long result = 1;
while (exponent != 0) {
result *= base;
--exponent;
}
System.out.println("Result: " + result);
}
}
Output:
Result: 32
- Check Armstrong Number
Title: Armstrong Number
public class ArmstrongNumber {
public static void main(String[] args) {
int number = 153;
int originalNumber = number;
int result = 0;
int n = 0;
while (originalNumber != 0) {
originalNumber /= 10;
++n;
}
originalNumber = number;
while (originalNumber != 0) {
int remainder = originalNumber % 10;
result += Math.pow(remainder, n);
originalNumber /= 10;
}
if (result == number) {
System.out.println(number + " is an Armstrong number.");
} else {
System.out.println(number + " is not an Armstrong number.");
}
}
}
Output:
153 is an Armstrong number.
- Check Palindrome Number
Title: Palindrome Number
public class PalindromeNumber {
public static void main(String[] args) {
int number = 12321;
int reversed = 0;
int originalNumber = number;
while (originalNumber != 0) {
int remainder = originalNumber % 10;
reversed = reversed * 10 + remainder;
originalNumber /= 10;
}
if (number == reversed) {
System.out.println(number + " is a palindrome number.");
} else {
System.out.println(number + " is not a palindrome number.");
}
}
}
Output:
12321 is a palindrome number.
- Calculate Average of Numbers
Title: Average Calculation
public class Average {
public static void main(String[] args) {
int[] numbers = {5, 7, 10, 12, 15};
int sum = 0;
for (int number : numbers) {
sum += number;
}
double average = (double) sum / numbers.length;
System.out.println("Average: " + average);
}
}
Output:
Average: 9.8
- Find the Largest Element in an Array
Title: Largest Element
public class LargestElement {
public static void main(String[] args) {
int[] numbers =
{5, 7, 10, 12, 15};
int largest = numbers[0];
for (int i = 1; i < numbers.length; i++) {
if (numbers[i] > largest) {
largest = numbers[i];
}
}
System.out.println("Largest element: " + largest);
}
}
Output:
Largest element: 15
- Find the Smallest Element in an Array
Title: Smallest Element
public class SmallestElement {
public static void main(String[] args) {
int[] numbers = {5, 7, 10, 12, 15};
int smallest = numbers[0];
for (int i = 1; i < numbers.length; i++) {
if (numbers[i] < smallest) {
smallest = numbers[i];
}
}
System.out.println("Smallest element: " + smallest);
}
}
Output:
Smallest element: 5
- Count the Number of Vowels in a String
Title: Vowel Count
public class VowelCount {
public static void main(String[] args) {
String str = "Hello, World!";
int count = 0;
str = str.toLowerCase();
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
count++;
}
}
System.out.println("Number of vowels: " + count);
}
}
Output:
Number of vowels: 3
- Reverse a String
Title: Reverse String
public class ReverseString {
public static void main(String[] args) {
String str = "Hello, World!";
String reversed = "";
for (int i = str.length() - 1; i >= 0; i--) {
reversed += str.charAt(i);
}
System.out.println("Reversed string: " + reversed);
}
}
Output:
Reversed string: !dlroW ,olleH
- Check if a String is a Palindrome
Title: Palindrome String
public class PalindromeString {
public static void main(String[] args) {
String str = "madam";
String reversed = "";
for (int i = str.length() - 1; i >= 0; i--) {
reversed += str.charAt(i);
}
if (str.equalsIgnoreCase(reversed)) {
System.out.println(str + " is a palindrome string.");
} else {
System.out.println(str + " is not a palindrome string.");
}
}
}
Output:
madam is a palindrome string.
- Generate a Random Number
Title: Random Number
import java.util.Random;
public class RandomNumber {
public static void main(String[] args) {
Random random = new Random();
int randomNumber = random.nextInt(100);
System.out.println("Random number: " + randomNumber);
}
}
Output:
Random number: (a random number between 0 and 99)
- Check if a Number is a Perfect Number
Title: Perfect Number
public class PerfectNumber {
public static void main(String[] args) {
int number = 28;
int sum = 0;
for (int i = 1; i <= number / 2; i++) {
if (number % i == 0) {
sum += i;
}
}
if (sum == number) {
System.out.println(number + " is a perfect number.");
} else {
System.out.println(number + " is not a perfect number.");
}
}
}
Output:
28 is a perfect number.
- Find the GCD (Greatest Common Divisor) of Two Numbers
Title: GCD Calculation
public class GCD {
public static void main(String[] args) {
int num1 = 36;
int num2 = 48;
int gcd = 1;
for (int i = 1; i <= num1 && i <= num2; i++) {
if (num1 % i == 0 && num2 % i == 0) {
gcd = i;
}
}
System.out.println("GCD of " + num1 + " and " + num2 + ": " + gcd);
}
}
Output:
GCD of 36 and 48: 12
- Convert Decimal to Binary
Title: Decimal to Binary Conversion
public class DecimalToBinary {
public static void main(String[] args) {
int decimalNumber = 25;
String binary = "";
while (decimalNumber > 0) {
binary = (decimalNumber % 2) + binary;
decimalNumber /= 2;
}
System.out.println("Binary representation: " + binary);
}
}
Output:
Binary representation: 11001
- Convert Binary to Decimal
Title: Binary to Decimal Conversion
public class BinaryToDecimal {
public static void main(String[] args) {
String binary = "11001";
int decimalNumber = 0;
for (int i = 0; i < binary.length(); i++) {
int digit = binary.charAt(i) - '0';
decimalNumber = decimalNumber * 2 + digit;
}
System.out.println("Decimal representation: " + decimalNumber);
}
}
Output:
Decimal representation: 25
- Calculate the Area of a Triangle
Title: Triangle Area
public class TriangleArea {
public static void main(String[] args) {
double base = 5.0;
double height = 8.0;
double area = 0.5 * base * height;
System.out.println("Area of the triangle: " + area);
}
}
Output:
Area of the triangle: 20.0
- Check if a Number is a Prime Number using a Function
Title: Prime Number (Function)
public class PrimeNumber {
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;
}
public static void main(String[] args) {
int number = 17;
if (isPrime(number)) {
System.out.println(number + " is a prime number.");
} else {
System.out.println(number + " is not a prime number.");
}
}
}
Output:
17 is a prime number.
- Calculate the Factorial of a Number using a Function
Title: Factorial Calculation (Function)
public class Factorial {
public static int factorial(int num) {
int result = 1;
for (int i = 1; i <= num; i++) {
result *= i;
}
return result;
}
public static void main(String[] args) {
int number = 5;
int factorial = factorial(number);
System.out.println("Factorial of " + number + ": " + factorial);
}
}
Output:
Factorial of 5: 120
- Generate Fibonacci Series
Title: Fibonacci Series
public class FibonacciSeries {
public static void main(String[] args) {
int count = 10;
int num1 = 0, num2 = 1;
System.out.print("Fibonacci Series: " + num1 + ", " + num2);
for (int i = 2; i < count; i++) {
int nextNum = num1 + num2;
System.out.print(", " + nextNum);
num1 = num2;
num2 = nextNum;
}
System.out.println();
}
}
Output:
Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34
- Check if Two Strings are Anagrams
Title: Anagram Strings
import java.util.Arrays;
public class AnagramStrings {
public static boolean areAnagrams(String str1, String str2) {
if (str1.length() != str2.length()) {
return false;
}
char[] charArray1 = str1.toCharArray();
char[] charArray2 = str2.toCharArray();
Arrays.sort(charArray1);
Arrays.sort(charArray2);
return Arrays.equals(charArray1, charArray2);
}
public static void main(String[] args) {
String str1 = "listen";
String str2 = "silent";
if (areAnagrams(str1, str2)) {
System.out.println(str1 + " and " + str2 + " are anagrams.");
} else {
System.out.println(str1 + " and " + str2 + " are not anagrams.");
}
}
}
Output:
listen and silent are anagrams.
- Find the Sum of Natural Numbers
Title: Sum of Natural Numbers
public class SumOfNaturalNumbers {
public static void main(String[] args) {
int n = 10;
int sum = 0;
for (int i = 1; i <= n; i++) {
sum += i;
}
System.out.println("Sum of natural numbers from 1 to " + n + ": " + sum);
}
}
Output:
Sum of natural numbers from 1 to 10: 55
- Calculate the Average of an Array
Title: Array Average
public class ArrayAverage {
public static void main(String[] args) {
int[] numbers = {5, 7, 10, 12, 15};
int sum = 0;
for (int number : numbers) {
sum += number;
}
double average = (double) sum / numbers.length;
System.out.println("Average of the array: " + average);
}
}
Output:
Average of the array: 9.8
- Check if a Number is a Perfect Square
Title: Perfect Square
public class PerfectSquare {
public static void main(String[] args) {
int number = 16;
if (Math.sqrt(number) % 1 == 0) {
System.out.println(number + " is a perfect square.");
} else {
System.out.println(number + " is not a perfect square.");
}
}
}
Output:
16 is a perfect square.
- Find the Factorial of a Number using Recursion
Title: Factorial Calculation (Recursion)
public class Factorial {
public static int factorial(int num) {
if (num == 0 || num == 1) {
return 1;
}
return num * factorial(num - 1);
}
public static void main(String[] args) {
int number = 5;
int factorial = factorial(number);
System.out.println("Factorial of " + number + ": " + factorial);
}
}
Output:
Factorial of 5: 120
- Reverse an Array
Title: Reverse Array
import java.util.Arrays;
public class ReverseArray {
public static void main(String[] args) {
int[] numbers = {5, 7, 10, 12, 15};
System.out.println("Original Array: " + Arrays.toString(numbers));
for (int i = 0; i < numbers.length / 2; i++) {
int temp = numbers[i];
numbers[i] = numbers[numbers.length - 1 - i];
numbers[numbers.length - 1 - i] = temp;
}
System.out.println("Reversed Array: " + Arrays.toString(numbers));
}
}
Output:
Original Array: [5, 7, 10, 12, 15] Reversed Array: [15, 12, 10, 7, 5]
- Count the Frequency of Each Element in an Array
Title: Element Frequency
import java.util.HashMap;
import java.util.Map;
public class ElementFrequency {
public static void main(String[] args) {
int[] numbers = {5, 7, 10, 7, 12, 15, 7};
Map<Integer, Integer> frequencyMap = new HashMap<>();
for (int number : numbers) {
frequencyMap.put(number, frequencyMap.getOrDefault(number, 0) + 1);
}
for (Map.Entry<Integer, Integer> entry : frequencyMap.entrySet()) {
System.out.println("Frequency of " + entry.getKey() + ": " + entry.getValue());
}
}
}
Output:
Frequency of 5: 1 Frequency of 7: 3 Frequency of 10: 1 Frequency of 12: 1 Frequency of 15: 1
- Find the Second Largest Element in an Array
Title: Second Largest Element
public class SecondLargestElement {
public static void main(String[] args) {
int[] numbers = {5, 7, 10, 12, 15};
int largest = numbers[0];
int secondLargest = Integer.MIN_VALUE;
for (int i = 1; i < numbers.length; i++) {
if (numbers[i] > largest) {
secondLargest = largest;
largest = numbers[i];
} else if (numbers[i] > secondLargest && numbers[i] != largest) {
secondLargest = numbers[i];
}
}
System.out.println("Second largest element: " + secondLargest);
}
}
Output:
Second largest element: 12
- Merge Two Arrays and Sort the Resulting Array
Title: Merge and Sort Arrays
import java.util.Arrays;
public class MergeAndSortArrays {
public static void main(String[] args) {
int[] arr1 = {2, 4, 6, 8};
int[] arr2 = {1, 3, 5, 7};
int[] mergedArray = new int[arr1.length + arr2.length];
System.arraycopy(arr1, 0, mergedArray, 0, arr1.length);
System.arraycopy(arr2, 0, mergedArray, arr1.length, arr2.length);
Arrays.sort(mergedArray);
System.out.println("Merged and Sorted Array: " + Arrays.toString(mergedArray));
}
}
Output:
Merged and Sorted Array: [1, 2, 3, 4, 5, 6, 7, 8]
- Check if a Year is a Leap Year
Title: Leap Year
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.");
}
}
}
Output:
2024 is a leap year.
- Calculate the Power of a Number
Title: Power Calculation
public class Power {
public static double power(double base, int exponent) {
double result = 1;
for (int i = 1; i <= Math.abs(exponent); i++) {
result *= base;
}
if (exponent < 0) {
result = 1 / result;
}
return result;
}
public static void main(String[] args) {
double base = 2;
int exponent = 5;
double powerResult = power(base, exponent);
System.out.println(base + " raised to the power of " + exponent
+ ": " + powerResult);
}
}
Output:
2.0 raised to the power of 5: 32.0
We have seen 40 Java Programs which will help you to get good knowledge of basic programming.
Happy Learning.