package java.util;

/**
 * The <code>Stack</code> class represents a last-in-first-out (LIFO) stack of objects. It extends
 * class <code>Vector</code> with five operations that allow a vector to be treated as a stack. The
 * usual <code>push</code> and <code>pop</code> operations are provided, as well as a method to
 * <code>peek</code> at the top item on the stack, a method to test for whether the stack is
 * <code>empty</code>, and a method to <code>search</code> the stack for an item and discover how far it is
 * from the top.
 * <p>
 * When a stack is first created, it contains no items.
 *
 * @param <E> the type of the elements in this stack
 */
public class Stack<E> extends Vector<E> {

    /**
     * Creates an empty Stack.
     */
    public Stack() {
        throw new RuntimeException();
    }

    /**
     * Tests if this stack is empty.
     *
     * @return <code>true</code> if and only if this stack contains no items; <code>false</code>
     *         otherwise.
     */
    public boolean empty() {
        throw new RuntimeException();
    }

    /**
     * Looks at the object at the top of this stack without removing it from the stack.
     *
     * @return the object at the top of this stack (the last item of the <code>Vector</code> object).
     * @throws EmptyStackException
     *         if this stack is empty.
     */
    public E peek() {
        throw new RuntimeException();
    }

    /**
     * Removes the object at the top of this stack and returns that object as the value of this
     * function.
     *
     * @return The object at the top of this stack (the last item of the <code>Vector</code> object).
     * @throws EmptyStackException
     *         if this stack is empty.
     */
    public E pop() {
        throw new RuntimeException();
    }

    /**
     * Pushes an item onto the top of this stack. This has exactly the same effect as: <blockquote>
     *
     * <pre>
     * addElement(item)
     * </pre>
     *
     * </blockquote>
     *
     * @param item
     *        the item to be pushed onto this stack.
     * @return the <code>item</code> argument.
     * @see java.util.Vector#addElement
     */
    public E push(E item) {
        throw new RuntimeException();
    }

    /**
     * Returns the 1-based position where an object is on this stack. If the object <code>o</code> occurs as
     * an item in this stack, this method returns the distance from the top of the stack of the
     * occurrence nearest the top of the stack; the topmost item on the stack is considered to be at
     * distance <code>1</code>. The <code>equals</code> method is used to compare <code>o</code> to the items in
     * this stack.
     *
     * @param o
     *        the desired object.
     * @return the 1-based position from the top of the stack where the object is located; the return
     *         value <code>-1</code> indicates that the object is not on the stack.
     */
    public int search(Object o) {
        throw new RuntimeException();
    }
}