Factorial Program in Java (Find Factorial of a Number in Java)
Let’s learn how to find the factorial of a number in Java!
Factorial is a fundamental mathematical concept that represents the product of all positive integers up to a given number. As a Java enthusiast, understanding various techniques to calculate factorial of a number is crucial for solving a wide range of computational problems efficiently.
In this tutorial, you will learn about the factorial program in Java with different approaches. Each approach, like factorial program using recursion in Java, offers unique insights into handling factorials, enabling you to choose the most appropriate approach for different scenarios and optimize your code accordingly.
Java Concepts to Learn for This Program:
So, let’s get started and practice the factorial code in Java!
Factorial Program in Java Using Recursion
Here's a program to calculate the factorial of a number using recursion in Java:
Code
import java.util.Scanner;
public class FactorialCalculator {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (number < 0) {
System.out.println("Factorial is not defined for negative numbers.");
} else {
long factorial = calculateFactorial(number);
System.out.println("Factorial of " + number + " is: " + factorial);
}
}
private static long calculateFactorial(int n) {
if (n == 0 || n == 1) {
return 1;
} else {
return n * calculateFactorial(n - 1);
}
}
}Output
Enter a number: 7
Factorial of 7 is: 5040Explanation
This program takes a non-negative integer as input from the user and calculates its factorial using a recursive approach. The factorial of a non-negative integer 'n' is the product of all positive integers from 1 to 'n'.
If the user enters a negative number, it will display a message saying that the factorial is not defined for negative numbers. Otherwise, it will calculate and display the factorial of a number using recursion in Java.
Factorial Program in Java Using Scanner
Here's a program to calculate the factorial of a number using scanner in Java:
Code
import java.util.Scanner;
public class FactorialCalculator {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (number < 0) {
System.out.println("Factorial is not defined for negative numbers.");
} else {
long factorial = calculateFactorial(number);
System.out.println("Factorial of " + number + " is: " + factorial);
}
}
private static long calculateFactorial(int n) {
if (n == 0 || n == 1) {
return 1;
} else {
long factorial = 1;
for (int i = 1; i <= n; i++) {
factorial *= i;
}
return factorial;
}
}
}Output
Enter a number: 9
Factorial of 9 is: 362880Explanation
The Scanner class provides various methods to read different types of input. In this case, we use scanner.nextInt() to read an integer input from the user.
If the user enters a negative number, the program displays a message saying that the factorial is not defined for negative numbers. Otherwise, it calculates and displays the factorial of the given input using the calculateFactorial method.
Java Factorial Program Using BigInteger
Here's a Java program to calculate the factorial of a given number using BigInteger to handle large factorial values:
Code
import java.math.BigInteger;
import java.util.Scanner;
public class FactorialCalculator {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a non-negative integer: ");
int number = scanner.nextInt();
if (number < 0) {
System.out.println("Factorial is not defined for negative numbers.");
} else {
BigInteger factorial = calculateFactorial(number);
System.out.println("Factorial of " + number + " is: " + factorial);
}
}
private static BigInteger calculateFactorial(int n) {
BigInteger factorial = BigInteger.ONE;
for (int i = 1; i <= n; i++) {
factorial = factorial.multiply(BigInteger.valueOf(i));
}
return factorial;
}
}Output
Enter a non-negative integer: 31
Factorial of 31 is: 8222838654177922817725562880000000Explanation
BigInteger is a class in Java's java.math package that allows the representation and manipulation of integers of arbitrary precision. It can handle numbers that are too large to be represented using standard integer data types like int or long.
The program takes a non-negative integer as input from the user and calculates its factorial using a BigInteger variable. It iterates through each number from 1 to the given input and multiplies it with the current value of the BigInteger factorial variable. This ensures that the program can handle large factorial values accurately.
Note that the BigInteger class requires importing java.math.BigInteger to be used in the program.
Java Factorial Program Using for loop
Here's a factorial program in Java using a for loop:
Code
import java.util.Scanner;
public class FactorialCalculator {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
System.out.print("Enter a number: ");
int number = scanner.nextInt();
if (number < 0) {
System.out.println("Factorial is not defined for negative numbers.");
} else {
long factorial = calculateFactorial(number);
System.out.println("Factorial of " + number + " is: " + factorial);
}
}
private static long calculateFactorial(int n) {
long factorial = 1;
for (int i = 1; i <= n; i++) {
factorial *= i;
}
return factorial;
}
}Output
Enter a number: 5
Factorial of 5 is: 120Explanation
This program takes a non-negative integer as input from the user and calculates its factorial using a for loop.
The factorial of a non-negative integer 'n' is the product of all positive integers from 1 to 'n'.
For example, the factorial of 5 is 5 * 4 * 3 * 2 * 1 = 120.
If the user enters a negative number, it will display a message saying that the factorial is not defined for negative numbers. Otherwise, it will calculate and display the factorial of the given input using a for loop.