palindrome substring in java code example

Example 1: Java program to check palindrome string using recursion

import java.util.Scanner;
public class RecursivePalindromeJava 
{
   // to check if string is palindrome using recursion
   public static boolean checkPalindrome(String str)
   {
      if(str.length() == 0 || str.length() == 1)
         return true; 
      if(str.charAt(0) == str.charAt(str.length() - 1))
         return checkPalindrome(str.substring(1, str.length() - 1));
      return false;
   }
   public static void main(String[]args)
   {
      Scanner sc = new Scanner(System.in);
      System.out.println("Please enter a string : ");
      String strInput = sc.nextLine();
      if(checkPalindrome(strInput))
      {
         System.out.println(strInput + " is palindrome");
      }
      else
      {
         System.out.println(strInput + " not a palindrome");
      }
      sc.close();
   }
}

Example 2: Java program to check whether string is palindrome using library methods

public class StringPalindromeJava
{
   public static void isPalindrome(String str)
   {
      String strReverse = new StringBuffer(str).reverse().toString();
       // checking for palindrome
      if(str.equals(strReverse))
      {
         System.out.println(str + " is palindrome string.");
      }
      else
      {
         System.out.println(str + " is not palindrome string.");
      }
   }
   public static void main(String[] args)
   {
      // palindrome java
      isPalindrome("eye");
      isPalindrome("rotator");
   }
}

Example 3: palindrome number in java

import java.util.Scanner;

public class Palindrome
{
  public static void main(String args[])
  {
    int num,temp,reverse=0;
    Scanner input=new Scanner(System.in);
    num=in.nextInt();
    temp=num;
    //code to reverse the number
    while(temp!=0)
    {
      int d=temp%10; //extracts digit at the end
      reverse=reverse*10+d;
      temp/=10; //removes the digit at the end
    }
    // 'reverse' has the reverse version of the actual input, so we check
    if(reverse==num)
    {
      System.out.println("Number is palindrome");
    }
    else
    {
      System.out.println("Number is not palindrome");
    }
  }
}