Palindrome program with reverse method

I wrote a program for a college assignment, and I'd like to receive some pointers on making my code a little more efficient.


The program should ask the end user to enter an integer. Use the
isPalidrome method to invoke the reverse method, and report whether
the integer is a palindrome. Any one-digit integer or negative
integer should be rejected with the specific error message (negative
or one digit), and then the program should ask the user to re-enter
the integer. Hint: To reverse the digits of a number, try this
routine:

int result = 0;                           
while (number != 0) {                   // e.g. number = 123
                                        // Iteration 1        Iteration 2    Iteration 3 
  int remainder = number % 10;          // remainder = 3      remainder = 2  remainder = 1 
  result = result * 10 + remainder;     // result = 3         result = 32    result = 321
  number = number / 10;                 // number = 12        number = 1     number = 0
}                                       // result contains the reverse of number

My solution:

```
package lab07;

import java.util.Scanner;
public class Lab07 {

public static int reverse(int number){

int result = 0;
while (number !=0){
int remainder = number % 10;
result = result * 10 + remainder;
number = number / 10;
}
return result;
}
public static boolean isPalindrome(int input){

int Palindrome = reverse(input);

if (Palindrome == input){

return true;
}
else
return false;
}
public static void main(String[] args) {

int integer = 0;
Scanner input = new Scanner(System.in);
System.out.print("Enter a positive, multi-digit integer: ");
integer = input.nextInt();
while (integer 0)
{
System.out.println(integer + " is a single digit. Please re-enter another integer: ");
integer = input.nextInt();

Apart from the other comments about how to calculate the input, I would also suggest that your main method is buggy, and not very 'pretty'. One the the tricks in programming that Java programmers seem to forget, is the do-while loop (note, C programmers use this all the time, and Java programmers do all sorts of crazy things to avoid it ...! ).

Consider the an altered main method

• renamed Scanner to be scanner

• renamed integer to be input.

• use do-while for input validation

• use 'simpler' printf for output

public static void main(String[] args) {

    int input = 0;
    Scanner scanner = new Scanner(System.in);      
    boolean ok = false;
    do {
        System.out.print("Enter a positive, multi-digit integer: ");
        input = scanner.nextInt();
        if (input < 0) {
            System.out.println(input + " is negative. Please re-enter another integer: ");
        } else if (input <= 9) {
            System.out.println(input + " is a single digit. Please re-enter another integer: ");
        } else {
            ok = true;
        }
    } while (!ok);

    System.out.printf("%d %s a palindrome\n", input, isPalindrome(input) ? "is" : "is not");
    scanner.close();

}

I should add that having 'return' in a main method is unconventional.... not 'wrong' but it probably means you are doing something weird...

StackExchange Code Review Q#33822, answer score: 5