//--------------------------------------------------------------------- // Palin

Question

//---------------------------------------------------------------------
// Palindrome.java by Dale/Joyce/Weems Chapter 4
//
// Provides a method to test whether a string is a palindrome.
// Non letters are skipped.
//---------------------------------------------------------------------
package ch04.palindromes;

import ch02.stacks.*;
import ch04.queues.*;

public class Palindrome
{
public static boolean test(String candidate)
// Returns true if candidate is a palindrome, false otherwise.
{
char ch; // current candidate character being processed
int length; // length of candidate string
char fromStack; // current character popped from stack
char fromQueue; // current character dequeued from queue
boolean stillPalindrome; // true if string might still be a palindrome

StackInterface<Character> stack; // holds non blank string characters
QueueInterface<Character> queue; // also holds non blank string characters

// initialize variables and structures
length = candidate.length();
stack = new ArrayBoundedStack<Character>(length);
queue = new ArrayBoundedQueue<Character>(length);

// obtain and handle characters
for (int i = 0; i < length; i++)
{
ch = candidate.charAt(i);
if (Character.isLetter(ch))
{
ch = Character.toLowerCase(ch);
stack.push(ch);
queue.enqueue(ch);
}
}
  
// determine if palindrome
stillPalindrome = true;
while (stillPalindrome && !stack.isEmpty())
{
fromStack = stack.top();
stack.pop();
fromQueue = queue.dequeue();
if (fromStack != fromQueue)
stillPalindrome = false;
}
  
// return result
return stillPalindrome;
}
}

How would you change the test method of the Palindrome class so that it considers all characters, not just letters? Identify the statements you would change, and how you would change them.

Explanation / Answer

for (int i = 0; i < length; i++)
{

//Removed the If condition check and upperCase thing so that it includes all the characters now
ch = candidate.charAt(i);
stack.push(ch);
queue.enqueue(ch);

}

Do not check for letters , add all the characters in the stack as well as in the queue

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