We need to write a safe enqueue() method that will fail when the queue is full. 

Steps for completion:

1. Modify the enqueue and dequeue methods shown in the preceding code so that the enqueue returns a Boolean value which is false when the queue is full and cannot accept further elements.
2. Implement the method signatures as follows:

public boolean enqueueSafe(V item)
public Optional<V> dequeueSafe()  

3. The following Snippet 2.26 provides an implementation of the enqueueSafe() method, returning a Boolean value when the queue is full:

private boolean full = false;
public boolean enqueueSafe(V item) {
  if (!full) {
    array[tailPtr] = item;
    tailPtr = (tailPtr + 1) % array.length;
    this.full = tailPtr == headPtr;
    return true;
  }
  return false;
}  

We have seen how both queues and stacks can be implemented using a static array structure instead of using the dynamic linked list. This has the advantage of consuming less memory per element as a linked list has to store pointers to other nodes. However, this comes at the cost of having a limit on the structure size.