I have a code to test a string of characters to see if they are in palindrome form. I get an error at on the last line saying Stringbuilder cannot be converted to String. I don't understand if I am building a string, how is that not a string. Also, part of the assignment was to create our own stack class. Mine is called MyStack, but I am not sure I am calling it anywhere except when I make a new stack. How do I call MyStack instead of the library stack?

```
public boolean isPalindrome(String line) throws StackException {
    MyStack Stack = new MyStack();
    // initialize loop counters
    int i = 0;
    int n = line.length();

    /* Push all char to a_stack */
    while (i < line.length()){
        char ch = line.charAt(i);
        Stack.push(ch);
        i++;
    }
    StringBuilder result = new StringBuilder();
    while (!Stack.empty()){
        result.append(Stack.pop());
    }
    result.toString();

    return inputString.equalsIgnoreCase(result);
}

```