Java - Using Recursion to Find Palindrome

Question

I am designing a util class that takes a string as a parameter and returns true if it is a palindrome(ex: input: radar ---> output: true) and returns false if it is not. For this class, I am using a linkedlist, however I don't know why there seems to be an error. Here is the stack trace:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 4, Size: 4
    at java.util.LinkedList.checkElementIndex(LinkedList.java:555)
    at java.util.LinkedList.remove(LinkedList.java:525)
    at com.run.FindPalindromes.FindMain(FindPalindromes.java:20)
    at com.run.FindPalindromes.FindMain(FindPalindromes.java:16)
    at com.run.Test.main(Test.java:7)

And Here is the source code:

public boolean FindMain(String in){
    if(times == 0){
    search = new LinkedList(cc.convertStringToArraylist(in)); 
    times ++;
    FindMain(null);
    } else {
        if(search.get(search.size()-1).equals(search.get(0))){
            search.remove(0);
            search.remove(search.size());
            FindMain(null);
        } else {
            System.out.println("Not Palindrome");
            return false;
        }
    }

    return true;

}

Vivin Paliath · Accepted Answer · 2015-07-08 02:17:52Z

3

search.remove(search.size()) should be search.remove(search.size() - 1) since lists are zero-based. If you have four elements your list indices run from 0 to 3, and so there is nothing at location 4.

Also your code as it stands won't handle empty lists very well, so that's something you need to check.

edited Jul 8, 2015 at 2:17

answered Jul 8, 2015 at 2:12

Vivin Paliath

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