Java Program To Find The Factorial Of A Number Using Recursion Entered By The User

In this Java Program, we calculate the factorial of the number using recursion entered by the user.

Factorial of n is the product of all the positive descending integers. It is denoted by n!

For example : 4! = 4 * 3 * 2 * 1 = 24

Logic : fact = fact * i;

Step 1 : Import Scanner Class

Step 2 : Create main method

Step 3 : Create scanner object for capturing the user input

Step 4 : Ask the user to enter the number

Step 5 : Store the entered value in the variable num

Step 6 : Call the user defined function fact

Step 7 : Print the number

Step 8 : Create a static function which returns 1

Step 9 : Create recursion function which calls itself

Program :

import java.util.Scanner;

public class FactorialDemo {

    public static void main(String[] args)

    {

        //Scanner object for capturing the user input

        Scanner sc = new Scanner(System.in);

        System.out.println("Enter the number:");

        //Store the entered value in variable

        int num =sc.nextInt();

        //Call the user defined function fact

        int factorial = fact(num);

        System.out.println("Factorial of entered number is:"+factorial);

    }

    static int fact(int n)

    {

        int output;

        if(n==1){

            return 1;

        }

                //Recursion: Function calling itself

        output = fact(n-1)*n;

        return output;

    }    

}

Output :

Enter the number:

5

Factorial of entered number is:120

For execution of the same do visit my YouTube Channel :

https://youtu.be/IBSxhMDbMrw

Java Program To Reverse a String Entered by the User

In this Java Program, we reverse a string entered by the user

Logic :  String reversed = reverseString(str);

Step 1 : Import Scanner Class

Step 2 : Create main method

Step 3 : Create variable str

Step 4 : Ask user to enter the username

Step 5 : Create the object of the Scanner Class

Step 6 : Store the user entered username in the variable str

Step 7 : Close the scanner class to avoid memory lea

Step 8 : Apply the logic

Step 9 : Print the reversed string

Step 10 : Create reversedString method

Step 11 : Apply if condition which says if str is empty then reverse string

Step 12 : Call the function recursively 

Program :

import java.util.Scanner;

public class JavaExample2 {

    public static void main(String[] args)

    {

        String str;

        System.out.println("Enter your username:");

        Scanner sc = new Scanner(System.in);

        str = sc.nextLine();

        sc.close();

        String reversed = reverseString(str);

        System.out.println("The reversed string is:"+reversed);

    }

    public static String reverseString(String str)

    {

        if(str.isEmpty())

            return str;

        //calling function recursively

        return reverseString(str.substring(1))+str.charAt(0);

    }

}

Output :

Enter your username:

how are you doing?

The reversed string is:?gniod uoy era woh

For execution of the same do visit my Youtube Channel :

https://youtu.be/GUoz8dR5d1E

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