For the longest time, I considered myself to be a pretty good Java programmer. After all, I had been programming in Java for the last 7 years. But that was before I discovered the amazing world of palindromes and their applications to programming. Now, I feel like a Java master!
What is a Palindrome?
A palindrome is any string that reads the same forwards as backwards, such as “pop” or “tacocat”. While it’s not immediately obvious, palindromes are extremely useful in programming. Therefore, learning how to write a palindrome in Java is an important milestone for every programmer.
How to Write a Palindrome in Java
Writing a palindrome in Java requires very little code! In fact, you only need two things: (1) an empty string and (2) the ability to reverse that string. You can use this code template:
Ever wonder how to write a palindrome? A palindrome is a word that is spelled the same backward as forward. The following Java program shows how to write a palindrome program in Java.
The first step to writing a palindrome program in Java is to get the user input. In this case, we will use a string. Because strings in Java are immutable, we need to convert the string into an array of characters so we can reverse it.
Next, we create a copy of the array but reversed. We will then check if the reversed array matches the original array. If it does, we have ourselves a palindrome!
package com.javacodegeeks.corejava.palindrome;
/**
*
* @author http://www.javacodegeeks.com/2014/05/how-to-write-a-palindrome-in-java.html
*/
public class Palindrome {
private static boolean isPalindrome(String str) {
int length = str.length();
if (length == 0 || length == 1) {
return true;
}
char[] array = str.toCharArray();
int mid = length / 2;
for (int i = 0; i < mid; i++) { if (array[i] != array[length - 1 - i]) { return false; } } return true; } public static void main(String[] args) { String palindrome1 = "noon"; //Simple palindrom example String palindrome2 = "civic"; //Another palindrom example System.out.println("Palindrome1: " + palindrome A palindrome is a word, number, phrase, or other sequence of characters which reads the same backward as forward, such as madam or racecar or the number 10201. Sentence-length palindromes may be written when allowances are made for adjustments to capital letters, punctuation, and word dividers, such as "A man, a plan, a canal, Panama!", "Was it a car or a cat I saw?" or "No 'x' in Nixon". In this article we will show you how to write a palindrome program in Java without using string buffer. We will use character array and convert string into character array. public class PalindromeProgram { public static void main(String[] args) { String original = "madam"; int length = original.length(); char[] tempCharArray = new char[length]; char[] charArray = new char[length]; // put original string in an // array of chars for (int i = 0; i < length; i++) { tempCharArray[i] = original.charAt(i); } // A palindrome is a word that reads the same way forward and backwards. For example, if you looked at the word "noon" in the mirror, you'd be able to read it just as easily backwards as forwards. In this article we will use a Java program to show how to write a palindrome in Java. The first step is to create a new class in your favorite IDE (Intellij, Eclipse, Netbeans etc). Inside this class we will write our Java Palindrome code. public class Palindrome { public static void main(String[] args) { // code goes here } } In this blog post, we will write a palindrome program in Java that will be able to check for palindromes in a string. A palindrome is a word, phrase, number, or other sequence of characters which reads the same backward as forward, such as madam or racecar or the number 10201. Punctuation and spaces between the words or lettering is allowed. When writing our program, we will use an if statement to make sure that it checks if what we input is a palindrome by reversing the characters in the string we entered. First off, let's import java.util.*; so that we can use the Scanner class and System class. Then we will ask for input from the user by using a Scanner object to get the word or phrase they want to check for a palindrome. We then turn that input into lowercase so that it doesn't matter if they used uppercase letters in their word or phrase. Next, we create an empty string called reversedString which we will set equal to our original word or phrase but reversed by using a loop which runs through every character in our original input and concatenates each one to the beginning of our reversedString variable. After A palindrome is a word, phrase, or sequence that reads the same backward as forward. For example, madam is a palindrome. The first step in creating our Java program is to find out if the number is a palindrome. If the number is indeed a palindrome, we will go on to calculate the next smallest and largest palindromes. First things first! In order to see if the number is a palindrome, we need to reverse it. Let's create a method called reverse() which takes an int argument and returns an int. In this method, we are going to reverse the digits of our number by popping off each digit of the number using % (modulo) and /(division). We'll store these digits in a second array called reversedDigits[]. int[] reversedDigits = new int[digits.length]; for (int i = 0; i < digits.length; i++) { reversedDigits[i] = digits[digits.length - 1 - i]; }
