Recursion in Java

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This article explains about recursion in Java. We will learn what is recursion and how to use recursion to write effective Java programs.

This article is a part of our core java tutorial for beginners.

Recursion is a famous way to solve problems with less lines of code. Many programmers prefer recursion over iteration as less amount of code is required to solve problems using recursion.

For implementing recursion, we need to follow the below requirements:

• There should be a base case where the recursion terminates and returns a value.
• The value of the parameter(s) should change in the recursive call. Otherwise, this leads to infinite loop.

Let’s consider the code for finding factorial of a number using iteration as shown below:

int fact(int n)
{
   int r = 1;
   for(int i = n; i > 1 ; i--)
   {
      r = i * r;
   }
   return r;
}

Now, let’s consider the recursive solution for finding the factorial of a given number which is shown below:

int rfact(int n)
{
   if(n == 0 || n == 1)
      return 1;
   else
      return n * rfact(n-1);  //recursive call
}

The complete Java program which demonstrates recursion is given below:

class RecursionDemo
{
	public static void main(String[] args)
	{
		int n = 6;
		System.out.println("Factorial of " + n + " without recursion is: " + fact(n));
		System.out.println("Factorial of " + n + " using recursion is: " + rfact(n));
	}
	static int fact(int n)
	{
		int r = 1;
		for(int i = n; i > 1 ; i--)
		{
			r = i * r;
		}
		return r;
	}
	static int rfact(int n)
	{
		if(n == 0 || n == 1)
			return 1;
		else
			return n * rfact(n-1);  //recursive call
	}
}

Next let’s learn about command line arguments in java.

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.