Java Program to Find Factorial of a Number by Using Recursion

Prerequisite: Recursion in Java

In the previous article, we have discussed about Java Program to Add All the Numbers between a to b by Using Recursion

In this program we are going to see how to find factorial of a number using Recursion by Java programming language.

Java Program to Find Factorial of a Number by Using Recursion

Now let’s see different ways to find factorial of a number by Using Recursion.

By Using Static Input and Recursion
By Using User Input and Recursion

Method-1: Java Program to Find Factorial of a Number By Using Static Input and Recursion

Approach:

Declare and initiate two static integer variable say count and fact with the value of 0 and 1 respectively.
Declare and initiate an integer value n with a value.
Then call a user defined method calculateValue() and pass n as parameter.
Inside the user defined method write the logic to find factorial by using an If statement.
Call the same method inside that user defined method recursively till the target.
Print the result.

Program:

class Main
{
    //Declare and initiate two static integer variable say count and fact with the value of 0 and 1 respectively. 
    static int count=0,fact=1;
    public static void main(String[] args)
    {
        int n=10;
        calculateValue(n);
        System.out.print("Factorial of "+n+" is= "+fact);
    }
    
    //define the method
    public static void calculateValue(int n)
    {
        //Increase the value of count by 1
        count++;
        //Check the condition whether the value of count is continuing till the value reaches.
        if(count<=n)
        {
            fact*=count;
            //call the same function inside this user defined method
            calculateValue(n);
        }
    }
}

Output:

Factorial of 10 is= 3628800

Method-2: Java Program to Find Factorial of a Number By Using User Input and Recursion

Approach:

Declare and initiate two static integer variable say count and fact with the value of 0 and 1 respectively.
Declare and initiate an integer value n and prompt the user to enter the value.
Then call a user defined method calculateValue() and pass n as parameter.
Inside the user defined method write the logic to find factorial by using an If statement.
Call the same method inside that user defined method recursively till the target.
Print the result.

Program:

import java.util.Scanner;
class Main
{
    //Declare and initiate two static integer variable say count and fact with the value of 0 and 1 respectivily. 
    static int count=0,fact=1;
    public static void main(String[] args)
    {
        //create object of scanner class.
        Scanner sc=new Scanner(System.in);
        System.out.print("Enter a number: ");
        int n=sc.nextInt();
        calculateValue(n);
        System.out.print("Factorial of "+n+" is= "+fact);
    }
    
    //define the method
    public static void calculateValue(int n)
    {
        //Increase the value of count by 1
        count++;
        //Check the condition whether the value of count is continuing till the value reaches.
        if(count<=n)
        { 
            fact*=count;
            //call the same function inside this user defined method
            calculateValue(n);
        }
    }
}

Output:

Enter a number: 5
Factorial of 5 is= 120

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