Exception in thread main java.lang.arrayindexoutofboundsexception: 0 on line 47, whhhhhhhhy \ /

public class Problem2 {

public static boolean isSameWord(String str) { MyStack stack = new MyStack(); int top = -1; //using MyStack for (int i = 0; i < str.length(); i++) { stack.push(str.charAt(i)); top++; } //reversing to check is its equal String equals = ""; try { while (!stack.isEmpty()) { equals += stack.pop(); } } catch (NoSuchElementException e) { }

return equals.equals(str); }

public static void main(String[] args){ AvlTree wordTree = new AvlTree<>(); //command line argument if (args.length == 0) { System.out.println("Please provide filename as an argument:"); return; } String filename = args[0]; try { //reading in a file BufferedReader br = new BufferedReader(new FileReader(filename)); String line; int WordCount = 0; while ((line = br.readLine()) != null) { //taking away all the punctuation and spaces and making the line all lowercase String stripped = line.replace(". ", "").replace(", ", "").toLowerCase(); if (isSameWord(stripped)) { //declaring we found a match stripped = stripped.replaceFirst("^[^a-zA-Z']+", "").replaceAll("[^a-zA-Z']+$", "").toLowerCase(); wordTree.insert(stripped, WordCount); WordCount++; } wordTree.printTree(); } //if the input argument has no duplicate words at all if (WordCount == 0) { System.out.println("There are no duplicate words."); } br.close(); } catch (FileNotFoundException e) { System.out.println(filename + " does not exist."); } catch (IOException exception) { exception.printStackTrace(); } } }