Question

(Palindrome integer) Write the methods with the following headers // Return the reversal of an integer, i.e., reverse(456) returns 654 public static int reverse(int number) // Return true if number is a palindrome public static boolean isPalindrome(int number) Use the reverse method to implement isPalindrome. A number is a palindrome if its reversal is the same as itself. Write a test program that prompts the user to enter an integer and reports whether the integer is a palindrome.

Answer 1

Answer:

import java.util.Scanner;

public class PalindromeInteger {

public static void main(String[] args) {

 // Create an object of the Scanner class to allow for user's inputs

 Scanner input = new Scanner(System.in);

 // Create a prompt to display the aim of the program.

 System.out.println("Program to check whether or not a number is a palindrome");

 // Prompt the user to enter an integer number.

 System.out.println("Please enter an integer : ");

 // Receive user's input and store in an int variable, number.

 int number = input.nextInt();

 // Then, call the isPalindrome() method to check if or not the

 // number is a  palindrome integer.

 // Display the necessary output.

 if (isPalindrome(number)) {

  System.out.println(number + " is a palindrome integer");

 }

 else {

  System.out.println(number + " is a not a palindrome integer");

 }

}

// Method to return the reversal of an integer.

// It receives the integer as a parameter.

public static int reverse(int num) {

 // First convert the number into a string as follows:

 // Concatenate it with an empty quote.

 // Store the result in a String variable, str.

 String str = "" + num;

 // Create and initialize a String variable to hold the reversal of the  

 // string str. i.e rev_str

 String rev_str = "";

 // Create a loop to cycle through each character in the string str,

 // beginning at  the last character down to the first character.

 // At every cycle, append the character to the rev_str variable.

 // At the end of the loop, rev_str will contain the reversed of str

 for (int i = str.length() - 1; i >= 0; i--) {

  rev_str += str.charAt(i);

 }

 // Convert the rev_str to an integer using the Integer.parseInt()

 // method.  Store the result in an integer variable reversed_num.

 int reversed_num = Integer.parseInt(rev_str);

 // Return the reversed_num

 return reversed_num;

}

// Method to check whether or not a number is a palindrome integer.

// It takes in the number as parameter and returns a true or false.

// A number is a palindrome integer if reversing the number does not

//  change the  number itself.

public static boolean isPalindrome(int number) {

 // check if the number is the same as its reversal by calling the

 //reverse()  method declared earlier. Return true if yes, otherwise,

               // return false.

 if (number == reverse(number)) {

  return true;

 }

 return false;

}

}

Explanation:

The source code file for the program has also been attached to this response for readability. Please download the file and go through the comments in the code carefully as it explains every segment of the code.

Hope this helps!

Download java