The document describes a programming assignment to write a tail-recursive method that prints every alternate integer between two numbers entered by the user. It must prompt the user for the starting and ending numbers, call the tail-recursive method recursively to display each integer starting from the beginning number by 3s, and handle any runtime errors from invalid user input. The method should use print statements to show each recursive call along with the parameters and return value to demonstrate its tail-recursive nature.

1. In this programming assignment you are required to write a tail-recursive method that prints
every alternate integer between two specific integers. Programming: The main() program should
prompt the user to enter the beginning and the end number of the range. It then displays every
3rd integer starling from the beginning number. The end number may or may not be displayed.
For example: if user specifics 2 and 10, then the program displays 2, 5, 8. The next number is 11
that is beyond the last number, so it is not displayed. [Method must be tail-recursive] Use
appropriate print statements indicating the method call point and return of the answer to prove
the tail-recursive nature of the method. A sample output with initial input 2 and 10 could be as
follows: Recursive call not 1 Method call parameters: low = 2 and high = 10 Method returns: 2
Recursive call no: 2 Method call parameters: low = 5 and high = 10 Method returns: 5 Recursive
call no: 3 Method call parameters: low = 8 and high = 10 Method returns: 8 Tail-recursion ends.
Program terminates. Runtime errors should be handled properly. For example, if the user types a
non-numeric character or hits enter without typing a number etc.
Solution
import java.util.Scanner;
public class Tailrecursive {//class starts
static int cnt = 0;//counter
public static void tail_recursive(int b, int e)//takes two parameters begining integer and ending
integer
{
if (b <= e) {
System.out.println(" Recursive call no: " + (cnt + 1));
System.out.println(" Method call parameters: low = " + b + " and high = " + e + " method
returns: " + b);
cnt++;
tail_recursive(b + 3, e);//recursive calling
}
}
public static void main(String[] args) throws Exception {
Scanner s = new Scanner(System.in);//takes input from console
System.out.println("Enter the beginning integer");

2. int b = s.nextInt();
System.out.println("Enter the ending integer");
int e = s.nextInt();
tail_recursive(b, e);//function calling
System.out.println("Tail recursion ends. program terminates.");
}
}
output:
run:
Enter the beginning integer
2
Enter the ending integer
10
Recursive call no: 1
Method call parameters: low = 2 and high = 10 method returns: 2
Recursive call no: 2
Method call parameters: low = 5 and high = 10 method returns: 5
Recursive call no: 3
Method call parameters: low = 8 and high = 10 method returns: 8
Tail recursion ends. program terminates.
BUILD SUCCESSFUL (total time: 5 seconds)