IntStack.java

public class IntStack {
	/**
	 * The maximum size of this stack.
	 */
	private static final int MAX_SIZE = 100;

	/**
	 * The values stored in this stack. It should be initially empty.
	 */
	private int[] values;

	/**
	 * The number of valid elements in this stack. It should be initially 0 since we start with an empty stack.
	 */
	private int nvalid;

	/**
	 * Creates an initially empty stack.
	 */
	public IntStack() {
	}

	/**
	 * Pushes element onto this stack only if there is room.
	 * 
	 * @param element The element to push onto this stack.
	 */
	public void push(int element) {
	}

	/**
	 * Pops the last value pushed onto this stack. Has no affect if this stack
	 * is empty.
	 */
	public void pop() {
	}

	/**
	 * Returns the value at the top of this stack if the stack is non−empty,
	 * otherwise, throws an exception.
	 * 
	 * @return The element at the top of the stack if it exists.
	 * @throws IllegalStateException If the stack is empty.
	 */
	public int top() {
		return 0; //TODO.
	}

	/**
	 * Returns true if this stack is empty and false otherwise.
	 * 
	 * @return True if this stack is empty and false otherwise.
	 */
	public boolean isEmpty() {
		return false; //TODO.
	}
}