ReverseNumber.java

package com.examplehub.maths;

public class ReverseNumber {

  /**
   * Reverse a number.
   *
   * @param number the number to be reversed.
   * @return the reversed number of given number.
   */
  public static int reverse(int number) {
    int reversedNumber = 0;
    while (number != 0) {
      reversedNumber = reversedNumber * 10 + number % 10;
      number /= 10;
    }
    return reversedNumber;
  }

  /**
   * Reverse a number.
   *
   * @param number the number to be reversed.
   * @return the reversed number of given number.
   */
  public static int reverse2(int number) {
    boolean isNegative = number < 0;
    number = Math.abs(number);

    StringBuilder builder = new StringBuilder(number + "");
    builder = builder.reverse();
    return isNegative
        ? -Integer.parseInt(builder.toString())
        : Integer.parseInt(builder.toString());
  }
}