import java.util.Vector;
import java.util.EmptyStackException;
/**
* This class abstracts a Queue data structure, that is a
* first-in, first-out or FIFO list of objects.
* @version 1.0 of March 5, 1996
* @author Elliotte Rusty Harold
*/
public class Queue extends Vector {
/**
* This method puts an object at the back of the Queue.
* @param o The object to be added to the back of the Queue
*/
public void add(Object o) {
addElement(o);
}
/**
* This method takes the object from the front of the Queue.
* @return The object at the front of the Queue
*/
public Object remove() {
Object o = peek();
removeElementAt(0);
return o;
}
/**
* Look at the object at the front of the queue
* without removing it
* @return the object at the front of the Queue
* @throws EmptyStackException if the Queue is empty
*/
public Object peek() {
if (size() == 0) throw new EmptyStackException();
return elementAt(0);
}
/**
* Tests whether the Queue is empty
* @return true if the Queue is empty, otherwise false
*/
public boolean empty() {
return size() == 0;
}
}