Java Program to Add Two Numbers by Using Recursion

Java Program to Add Two Numbers by Using Recursion

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Prerequisite: Recursion in Java

In the previous article, we have discussed about Java Program to Check Armstrong Number by Using Recursion

In this program we are going to add two numbers by using recursion in Java programming language.

Java Program to Add Two Numbers by Using Recursion

Now let’s see different ways to add two numbers by using recursion.

Method-1: Java Program to Add Two Numbers By Using Static Input and Recursion

Approach:

  • Declare and initialize two integer variables say a, b
  • Declare another integer variable say sum to store the addition result.
  • Call a user defined method add() and pass a and b as parameter.
  • Then inside the user defined method check if ‘b’ is equals to 0 then  return ‘a‘ else return (1+add(a,b-1)) which will call the same method inside that user defined method.
  • Finally print the result.

Program:

class Main
{
    public static void main(String args[])
    {
        //Declare three integer variables
    	int sum,a=1,b=3;     
        System.out.println("Value for a: "+a); 
        System.out.println("Value for b: "+b);
        sum=add(a,b);         
   		System.out.print("Sum of two numbers are: "+sum);
    } 
    //Define the recursive method
    static int add(int a, int b)    
    {
    		if(b==0)
        		return a;
    		else
        		return(1+add(a,b-1));
    }
}

Output:
Value for a: 1
Value for b: 3
Sum of two numbers are: 4

Method-2: Java Program to Add Two Numbers By Using User Input and Recursion

Approach:

  • Declare two integer variables say a, b and take values input from user.
  • Declare another integer variable say sum to store the addition result.
  • Call a user defined method add() and pass a and b as parameter.
  • Then inside the user defined method check if ‘b’ is equals to 0 then  return ‘a‘ else return (1+add(a,b-1)) which will call the same method inside that user defined method.
  • Finally print the result.

Program:

import java.util.*;

class Main
{
    public static void main(String args[])
    {
        //create the object of scanner class
    	Scanner sc=new Scanner(System.in);
        System.out.print("Enter the value for a: ");
        //prompt the user to enter the value of a
        int a=sc.nextInt();                             
        System.out.print("Enter the value for b: ");
        //prompt the user to enter the value of b
        int b=sc.nextInt();
        //call the user defined method
        int sum=add(a,b);         
   		System.out.print("Sum of two numbers are: "+sum);
    } 
    //Define the recursive method
    static int add(int a, int b)    
    {
    		if(b==0)
        		return a;
    		else
        		return(1+add(a,b-1));
    }
}

Output:
Enter the value for a: 4
Enter the value for b: 2
Sum of two numbers are: 6

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