X382: LinkedStackToString

For the question below, assume the following implementation of LinkedStack:

​x
 
public class LinkedStack<T> implements StackInterface<T> {
    private Node<T> topNode;
    private int numberOfEntries;
​
    public LinkedStack() {
        this.topNode = null;
        numberOfEntries = 0;
    }// end default constructor
​
    @Override
    public void push(T newEntry) {
        topNode = new Node<T>(newEntry, topNode);
        numberOfEntries++;
    }
​
​
    @Override
    public T peek() {
        if (isEmpty()) {
            throw new EmptyStackException();
        }
        else {
            return (T)topNode.getData();
        }
    }// end peek
​
​
    @Override
    public T pop() {
        T top = peek();
        topNode = topNode.getNext();
        numberOfEntries--;
        return top;
    }
​
​
    @Override
    public boolean isEmpty() {
        return topNode == null;
    }
​
​
    @Override
    public void clear() {
        topNode = null;
    }
} // end LinkedStack
​
    public class Node<E> {
        private E data; // Entry in bag
        private Node<E> next; // Link to next node
​
        public Node(E dataPortion) {
            this(dataPortion, null);
        } // end constructor
​
​
        public Node(E dataPortion, Node<E> nextNode) {
            data = dataPortion;
            next = nextNode;
        } // end constructor
​
​
        public E getData() {
            if (data != null) {
                return data;
            }
            return null;
        }
​
​
        public Node<E> getNext() {
            return next;
        }
​
​
        public void setNext(Node<E> newNext) {
            next = newNext;
        }
    } // end Node

Below, you'll see most of a toString method implemented but a piece is missing. Currently the while loop will run infinitely. Add in the code to finish this method and the while loop will terminate when it is supposed to.

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