NextPalindrome.java

/*
For problem and solution description please visit the link below
http://www.dsalgo.com/2013/02/NextPalindrome.php.html
*/

package com.dsalgo;


public class NextPalindrome
{
 public static void main(String[] args)
 {
  System.out.println(nextPalindrome(112100));
 }
 public static int nextPalindrome(int num)
 {
  return nextPalindrome(num,true);
 }
 private static int nextPalindrome(int num,boolean firstTime)
 {
  String numString=""+num;
  int leftEndIndex=-1;
  int rightStartIndex=-1;
  boolean isOdd=numString.length()%2==1;
  if(isOdd)
  {
   leftEndIndex=numString.length()/2;
   rightStartIndex=leftEndIndex+1;
  }
  else
  {
   leftEndIndex=rightStartIndex=numString.length()/2;
   
  }
  String leftHalf=numString.substring(0,leftEndIndex);
  String rightHalf=numString.substring(rightStartIndex);
  
  String leftReversed=new StringBuffer(leftHalf).reverse().toString();
  String palindrome=null;
  if(Integer.parseInt(leftReversed)>Integer.parseInt(rightHalf)||!firstTime)
  {
   if(isOdd)
    palindrome=leftHalf+numString.charAt(leftEndIndex)+leftReversed;
   else
    palindrome=leftHalf+leftReversed;
   return Integer.parseInt(palindrome);
  }
  else
  {
   if(isOdd)
   {
    String leftAndMiddle=leftHalf+numString.charAt(leftEndIndex);
    int incrementedLeft=Integer.parseInt(leftAndMiddle)+1;
    return nextPalindrome(Integer.parseInt(incrementedLeft+rightHalf),false);
   }
   else
   {
    int incrementedLeft=Integer.parseInt(leftHalf)+1;
    return nextPalindrome(Integer.parseInt(incrementedLeft+rightHalf),false);
   }
  }
  
 }
}