Implement The Skeleton Code

package jp.co.worksap.global;

import java.util.NoSuchElementException;

/**

• The Queue class represents an immutable first-in-first-out (FIFO) queue of objects.

• @param <E>

*/

public class ImmutableQueue<E> {

/**

• requires default constructor.

*/

public ImmutableQueue() {

// modify this constructor if necessary, but do not remove default constructor

}

// add other constructors if necessary

/**

• Returns the queue that adds an item into the tail of this queue without modifying this queue.

• e.g.

• When this queue represents the queue (2, 1, 2, 2, 6) and we enqueue the value 4 into this queue,

• this method returns a new queue (2, 1, 2, 2, 6, 4)

• and this object still represents the queue (2, 1, 2, 2, 6) .

• If the element e is null, throws IllegalArgumentException.

• @param e

• @return

• @throws IllegalArgumentException

*/

public ImmutableQueue<E> enqueue(E e) {

return null;

}

/**

• Returns the queue that removes the object at the head of this queue without modifying this queue.

• e.g.

• When this queue represents the queue (7, 1, 3, 3, 5, 1) ,

• this method returns a new queue (1, 3, 3, 5, 1)

• and this object still represents the queue (7, 1, 3, 3, 5, 1) .

• If this queue is empty, throws java.util.NoSuchElementException.

• @return

• @throws java.util.NoSuchElementException

*/ public ImmutableQueue<E> dequeue() {

return null;

}

/**

• Looks at the object which is the head of this queue without removing it from the queue.

• e.g.

• When this queue represents the queue (7, 1, 3, 3, 5, 1),

• this method returns 7 and this object still represents the queue (7, 1, 3, 3, 5, 1)

• If the queue is empty, throws java.util.NoSuchElementException.

• @return

• @throws java.util.NoSuchElementException

*/

public E peek() {

return null;

}

/**

• Returns the number of objects in this queue.

• @return

*/

public int size() {

return -1;

}

}