Given the queue X that results from Exercise, what would be the result of each of the foll...

Given the queue X that results from Exercise, what would be the result of each of the following?

a. X.first();
b. Y = X.dequeue(); X.first();
c. Y = X.dequeue();
d. X.first()

Exercise

Hand trace a queue X through the following operations:

X.enqueue(new Integer(4));
X.enqueue(new Integer(1));
Object Y = X.dequeue();
X.enqueue(new Integer(8));
X.enqueue(new Integer(2))
 X.enqueue(new Integer(5));
X.enqueue(new Integer(3));
Object Y = X.dequeue();
X.enqueue(new Integer(4));
X.enqueue(new Integer(9));