Factorial Program Using Loop in Java

Factorial is a mathematical operation where a number is multiplied by all its preceding positive integers. It is denoted by n! and is calculated as follows:

Examples:

• 4! = 4 × 3 × 2 × 1 = 24
• 5! = 5 × 4 × 3 × 2 × 1 = 120

In this article, we will discuss how to calculate the factorial of a number using loops and recursion in Java.

Factorial Program Using Loop in Java

A loop-based approach iterates through all numbers up to the given number and multiplies them together to compute the factorial.

Example 1: Factorial Without Recursion (Using Loop)

class FactorialExample {
    public static void main(String args[]) {
        int i, fact = 1;
        int number = 5; // Number for factorial calculation  
        
        for (i = 1; i <= number; i++) {
            fact = fact * i;
        }
        
        System.out.println("Factorial of " + number + " is: " + fact);
    }
}

Explanation:

• We initialize fact = 1.
• We iterate from 1 to n and multiply fact by the loop variable.
• The final value of fact gives the factorial of the number.

Factorial Program Using Recursion in Java

A recursive approach solves the problem by calling the function repeatedly with a decremented value of n until n = 1.

Example 2: Factorial Using Recursion

public class FactorialRecursion {
    public static int factorial(int n) {
        if (n == 0 || n == 1) {
            return 1; // Base case
        } else {
            return n * factorial(n - 1); // Recursive call
        }
    }
    
    public static void main(String[] args) {
        int number = 5;
        System.out.println("Factorial of " + number + " is: " + factorial(number));
    }
}

Explanation:

• The function calls itself with n-1 until it reaches n=1.
• The recursion builds a call stack and returns the final product.
• This approach is more concise but may cause stack overflow for large values of n.

Conclusion

• Loop-based approach is efficient and does not consume additional stack memory.
• Recursive approach is elegant but can lead to stack overflow for large numbers.

Both methods are useful in different scenarios. Choose the best approach based on performance and readability.

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This article is contributed by the Developer Indian Team. If you find any mistakes or have suggestions, feel free to share your feedback!