Stack.java

/**
 * A linked list implementation of a stack
 *
 * @author William Fiset, william.alexandre.fiset@gmail.com
 */


public class Stack<T> implements Iterable<T> {

  private java.util.LinkedList<T> list = new java.util.LinkedList<T>();

  // Create an empty stack
  public Stack() {}

  // Create a Stack with an initial element
  public Stack(T firstElem) {
    push(firstElem);
  }

  // Return the number of elements in the stack
  public int size() {
    return list.size();
  }

  // Check if the stack is empty
  public boolean isEmpty() {
    return size() == 0;
  }

  // Push an element on the stack
  public void push(T elem) {
    list.addLast(elem);
  }

  // Pop an element off the stack
  // Throws an error is the stack is empty
  public T pop() {
    if (isEmpty()) throw new java.util.EmptyStackException();
    return list.removeLast();
  }

  // Peek the top of the stack without removing an element
  // Throws an exception if the stack is empty
  public T peek() {
    if (isEmpty()) throw new java.util.EmptyStackException();
    return list.peekLast();
  }

  // Allow users to iterate through the stack using an iterator
  @Override
  public java.util.Iterator<T> iterator() {
    return list.iterator();
  }
}