#Stack.java#

import java.util.NoSuchElementException;

public class Stack<T> implements StackADT<T> {
    private Object[] data;
    public Stack() {
	data = new Object[0];
    }
    public void push(T item) {
	Object[] tdata = new Object[data.length];
	for(int i = 0; i < data.length; i++) {
	    tdata[i] = data[i];
	}
	data = new Object[tdata.length+1];
	for(int i = 0; i < data.length; i++) {
	    data[i] = tdata[i];
	}
	data[data.length-1] = item;
    }
    public T dequeue() throws NoSuchElementException {
	Object[] tdata = new Object[data.length];
	for(int i = 0; i < data.length; i++) {
	    tdata[i] = data[i];
	}
	if(tdata.length > 1) {
	data = new Object[tdata.length-1];
	for(int i = 1; i < data.length; i++) {
	    data[i-1] = tdata[i];
	}
	return (T)tdata[0];
	} else {
	    throw new NoSuchElementException("You cannot pop a Stack with no elements");
	}
    }
    public T front() throws NoSuchElementException {
	if(data.length > 0) {
	    return (T)data[0];
	} else {
	    throw new NoSuchElementException("You cannot look at the top of a Stack with no elements");
	}
    }
    public int size() {
	return data.length;
    }
    public boolean isEmpty() {
	if(data.length > 0) {
	    return false;
	}
	return true;
    }
    public void clear() {
	data = new Object[0];
    }
}