How to find Palindrome in Java
Palindrome
It means a number or string remains same even if it is reversed/flipped. Let’s see how can we implement concept of palindrome for number and string as well.
Palindrome number:
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 |
package com.code2succeed.palindrome; public class palindrome { public static void main(String[] args) { //Check if number is Palindrome int n = 1221; System.out.println("Given number is-> " + n); boolean isPalindromenum = palindromenumber(n); System.out.println("Is given number is Palindrome? " + isPalindromenum); //Check if number is Palindrome int n1 = 1121; System.out.println("Given number is-> " + n1); boolean isPalindromenum = palindromenumber(n1); System.out.println("Is given number is Palindrome? " + isPalindromenum); } //Method to find Palindrome number public static boolean palindromenumber(int num) { int intialnum = num; int result = 0; int rem = 0; //Finding reverse of the given number while (num > 0) { rem = num % 10; result = result * 10 + rem; num = num / 10; } //Comparing if given number and reversed number are same if (intialnum == result) { return true; //Will return true if given number is palindrome } else { return false; // will return false is not palindrome } } } |
Output
|
1 2 3 4 |
Given number is-> 1221 Is given number is Palindrome? true Given number is-> 1121 Is given number is Palindrome? false |
Palindrome String:
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 |
package com.code2succeed.palindrome; public class palindrome { public static void main(String[] args) { //Check if string is Palindrome String str = "ilili"; System.out.println("Given string is-> " + str); boolean isPalindromestr = palindromestring(str); System.out.println("Is given string is Palindrome? " + isPalindromestr); //Check if string is Palindrome String str1 = "car"; System.out.println("Given string is-> " + str1); boolean isPalindromestr = palindromestring(str1); System.out.println("Is given string is Palindrome? " + isPalindromestr); } //Method to find Palindrome String public static boolean palindromestring(String str) { String reverseStr = ""; int length = str.length(); //Reverse the given string for (int i = length - 1; i >= 0; i--) { reverseStr = reverseStr + str.charAt(i); } //Comparing if given string and reversed string are same if (reverseStr.equals(str)) { return true; // will return true if it's palindrome } else { return false; // will return false if it's not palindrome } } } |
Output
|
1 2 3 4 |
Given string is-> ilili Is given string is Palindrome? true Given string is-> car Is given string is Palindrome? false |
We saw in above examples a method returns true if given number or string is Palindrome and false if it’s not palindrome.