Program is working but with error, String index out of range: -1

Question

this is my first post in here, btw, my teacher has given the class an assignment in programming in which we need to do a palindrome program, i'm able to do it but i wanted to get rid of the error, can you please explain me why there's an error, and how do I get rid of it?

import java.io.*;

public class AssignmentInCopro 

{public static void main (String [] args) throws IOException
    {BufferedReader x = new BufferedReader(new InputStreamReader(System.in));

    String word = "";

    System.out.print("Please enter the word you want to see in reverse: ");
    word = x.readLine();

    int wordLength = word.length(); 

    while (wordLength >=0)
    {
    char letter = word.charAt(wordLength - 1);
    System.out.print(letter);
    wordLength--;
    }
    }
}

Change the condition to wordLength > 0 (without the =).

Ingo Bürk
– Ingo Bürk

2014-09-07 08:18:42 +00:00
Commented Sep 7, 2014 at 8:18 — Ingo Bürk
– Ingo Bürk, Commented Sep 7, 2014 at 8:18

Jens · Accepted Answer · 2014-09-07 08:19:45Z

1

The error comes while your loop includet the index zero. If the wordLength is zero so you will look for the charAt(-1) and you get the exception:

Change your code to:

while (wordLength >0)

And the error is gone.

answered Sep 7, 2014 at 8:19

Jens

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Comments

Subhrajyoti Majumder · Accepted Answer · 2014-09-07 08:19:56Z

0

 while (wordLength >=0)

this cause error when wordLength =0 then char letter = word.charAt(wordLength - 1); is actually char letter = word.charAt(0 - 1);

while (wordLength >0)

This should be condition or you can write your loop like this -

int wordLength = word.length() - 1;
while (wordLength >=0){
    System.out.print(word.charAt(wordLength--));
}

answered Sep 7, 2014 at 8:19

Subhrajyoti Majumder

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Comments

Heaven42 · Accepted Answer · 2014-09-07 08:20:37Z

0

Look what happens when wordlength is actually equals to 0 //while (wordLength >=0) you trying to access char at -1 //word.charAt(wordLength - 1);

change it with while (wordLength >0) or while (wordLength >=1)

Have a nice day

answered Sep 7, 2014 at 8:20

Heaven42

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