basic-programs/java/PalindromeCheck.java at master · Scarlet-Coder/basic-programs · GitHub

45 lines (39 loc) · 1.75 KB

import java.util.Scanner;

/**

* To check if a given string is a palindrome

public class PalindromeCheck {

public static void main(String[] args) {

// Accept input from the console

System.out.print("Please enter a string: ");

String input = null;

String s = null;

try {

Scanner sc = new Scanner(System.in);

input = sc.next();

s = input.toLowerCase(); // convert all characters to lower case so that palindrome check is case insensitive.

sc.close();

} catch (Exception e) {

outputAndEnd("Unexpected error, please try to re-run the program."); // Error message for any unknown issues while reading the input

}

int len = s.length();

Loop through all the characters and evaluate if given string is a palindrome

For even length strings - Say SaaS (or Java)

S(J) and a(a) from beginning are compared against S(a) and a(v) from the end

For odd length strings - Say madam (or fruit)

m(f) and a(r) from beginning are compared against m(t) and a(i) from the end, the middle character d(u) is ignored

for (int i = 0; i < len / 2; i++) {

if (s.charAt(i) != s.charAt(len - 1 - i)) {

outputAndEnd(input + " is not a palindrome"); // Report failure when the first mismatch is found.

}

// If no mismatch is found and the loop is successfully complete, report the success.

outputAndEnd(input + " is a palindrome");

}

private static void outputAndEnd(String message) {

System.out.println(message); // output the given message

System.exit(0); // exit the program

}

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