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home / developersection / forums / what is recursion in java and also write code for reverse string?
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Ravi Vishwakarma
Ravi Vishwakarma

Software Developer

Hi, my self Ravi Vishwakarma. I have completed my studies at SPICBB Varanasi. now I completed MCA with 76% form Veer Bahadur Singh Purvanchal University Jaunpur. SWE @ MindStick | Software Engineer | Web Developer | .Net Developer | Web Developer | Backend Engineer | .NET Core Developer

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3 Answers

Krishnapriya Rajeev
Krishnapriya Rajeev 21 Mar 2023 Accepted Answer
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Recursion is the process in which a function calls itself directly or indirectly and the corresponding functions are called recursive functions.

Recursive function or method calls store new parameters and local variables on the stack, which are then removed as we return from the recursive calls. While recursive functions enable us to develop simple and clear solutions for certain problems easily, they can also lead to slow execution due to added overhead and additional function calls.

The concept of recursive function can be used to find the factorial of a number as shown below:

public class Main
{
	//recursive function for finding factorial
    static int factorial(int n)
    {
        if(n==1)
            return 1;
        else
            return(n*factorial(n-1));
    }
	public static void main(String[] args) {
		System.out.println("Factorial of 5 is: "+factorial(5));
	}
}

OUTPUT:
Factorial of 5 is: 120

Here, if factorial() is called with an argument of 1, then it returns 1 else it returns the product of n*factorial(n-1).

Code for reversing string using recursion in java

public class reverse
{  
//recursive function to reverse a string      
    public String reverseString(String str, String revstr)  
    {  
    //checks if the string is empty   
        if(str==null||str.length()==0)  
        {  
            return revstr;  
        }   
        else   
        {  
            return reverseString(str.substring(1), str.charAt(0)+revstr);  
        }  
}  

    public static void main(String[] args)   
    {  
        reverse rs = new reverse();  
        String reversedString = new String();
        reversedString = rs.reverseString("MINDSTICK","");  
        System.out.println(reversedString);   
    }  
}
Sanjay Goenka
Sanjay Goenka 06 Mar 2023 Accepted Answer
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I have no idea about the theory parts.

I try to write code for a reverse string in recursion.

function reverseString(s) {
   if (s.length == 0) {
       return s;
   }
   return reverseString(s.substring(1)) + s.charAt(0);
}

console.log(reverseString("kjhfdsfa-asdjhfkas-uw-1jas-5"));

Output →

5-saj1-wu-sakfhjdsa-afsdfhjk

I hope you enjoy this answer. Bye !!!

Amrita Bhattacharjee
Amrita Bhattacharjee 08 Feb 2023 Accepted Answer
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Recusion is a method where a function calls directly itself. In java, recursion is recognised as a process where any particular function calls itself. This process is used for avoiding difficult problems by making them comparatively easier. This method is used rarely and when any complicated type of code is needed to write then this process is used to make that simple. It is the process where the items are repeated in a same kind of manner.

The code for reverse string using recursion will be as follows:

public static String reverseString(String s) {
   if (s.length() == 0) {
       return s;
   }
   return reverseString(s.substring(1)) + s.charAt(0);
}
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