2 Consider that we can define the reverse of a string s recu

2. Consider that we can define the reverse of a string s recursively as:

reverse (s) = s if s.equals(\"\") (an empty string is its own reverse)

reverse (s) = s.charAt(s.length() - 1) + reverse(s.substring(0, s.length() - 1))

a) Create an application that prompts the user for a string, then outputs the string in reverse. For example, if the user inputs \"abcd efg,\" then your application should output \"gfe dcba.\" Within your application include a static recursive method reverse based on the above definition, that takes a String argument and returns a String that is the reverse of the argument.

b) Show the sequence of method calls to reverse that your application makes if the user inputs \"RECURSE.\"

Solution

The Java code where the string can be reveresed would be as under.

import java.util.*;
class ReverseString // declaring the class a Reverse String
{
public static void main(String args[])
{
String original, reverse = \"\";
Scanner in = new Scanner(System.in);
System.out.println(\"Enter a string to reverse\");// Asking the user to enter the text
original = in.nextLine();
int length = original.length();// Program capturing the origincal length of the string
for ( int i = length - 1 ; i >= 0 ; i-- )
reverse = reverse + original.charAt(i);
System.out.println(\"Reverse of entered string is: \"+reverse);// output of the string
}
}

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The sequence of method if the user inputs recursive

import java.util.Scanner;

class RecursionReverseDemo // declaring the class of RecursionReverseDemo
{
public static void reverseMethod(int number) {
if (number < 10) {
System.out.println(number);
return;
}
else {
System.out.print(number % 10);
//Method is calling itself: recursion
reverseMethod(number/10);
}
}
public static void main(String args[])
{
int num=0; System.out.println(\"Input your number and press enter: \");
Scanner in = new Scanner(System.in);
num = in.nextInt();
System.out.print(\"Reverse of the input number is:\");
reverseMethod(num);
System.out.println();//would print the recursive number
}
}

The above code would ask the user to enter the code and would return unlike wise as recursive.