Java- Find all possible Palindrome in given String

By Amit Kathuria | Last Updated: February 22, 2020 Previous       Next

In this short article, we’ll show you how to find all possible Palindrome in given String using Java.
Let us assume we have a string “ABACHCABCC”. It can have the following palindrome:

ABA
CC
ACHCA
BACHCAB
CHC

What is Palindrome?

A palindrome is a word, number, phrase, or other sequences of characters that reads the same backward as forward, such as madam, racecar. Wikipedia

package org.websparrow;

import java.util.HashSet;
import java.util.Set;

public class FindPalindrome {

	private Set<String> palindrome = new HashSet<>();

	public static void main(String[] args) {

		FindPalindrome findPalindrome = new FindPalindrome();
		findPalindrome.findPalindrome("ABACHCABCC");
		findPalindrome.print();

	}

	public void findPalindrome(String str) {
		if (str.length() == 1) {
			return;
		}
		int x = str.length() / 2;
		String str1 = str.substring(0, x);
		String str2 = str.replaceFirst(str1, "");
		for (int i = x; i >= 0; i--) {
			for (int j = 1; j <= str2.length(); j++) {
				String testPalindrome = str1.substring(i, str1.length())
						+ str2.substring(0, j);
				if (testPalindrome.length() > 1
						&& isPalindrome(testPalindrome)) {
					palindrome.add(testPalindrome);
				}
			}
		}

		findPalindrome(str1);
		findPalindrome(str2);
	}

	public boolean isPalindrome(String str) {
		char[] ch1 = str.toCharArray();
		char[] ch2 = str.toCharArray();
		for (int i = 0; i < ch1.length; i++) {
			ch2[i] = ch1[ch1.length - i - 1];
		}
		String revString = String.valueOf(ch2);

		return str.equals(revString);

	}

	public void print() {
		System.out.println("Total count of Palindrome: " + palindrome.size());
		palindrome.forEach(System.out::println);
	}
}

Output

Total count of Palindrome: 5
ABA
CC
ACHCA
BACHCAB
CHC