Source of 8.31.java

Structures and functions

  1: // @author Frank M. Carrano, Timothy M. Henry
  2: // @version 5.0
  3: public T removeFront()
  4: {
  5:    T front = getFront();  // Might throw EmptyQueueException
  6:    // Assertion: firstNode != null
  7:    firstNode = firstNode.getNextNode();

  9:    if (firstNode == null)
 10:       lastNode = null;
 11:    else
 12:       firstNode.setPreviousNode(null);

 14:    return front;
 15: } // end removeFront

 17: public T removeBack()
 18: {
 19:    T back = getBack();  // Might throw EmptyQueueException
 20:    // Assertion: lastNode != null
 21:    lastNode = lastNode.getPreviousNode();

 23:    if (lastNode == null)
 24:       firstNode = null;
 25:    else
 26:       lastNode.setNextNode(null);
 27:    } // end if

 29:    return back;
 30: } // end removeBack