Chapter 12, Problem 11PP

“LinkedQueue” class

Program Plan:

Filename: “LinkedQueue.java”

• Define “LinkedQueue” class.
  • Declare variable for reference of first node and number of items.
  • Default constructor for “LinkedQueue” class.
    • Set front to “null” and count to “0”.
  • Define the method “addToQueue()” with argument of “item”.
    • If “front” is not equal to “null”, then
      • Create a new node using “QueueNode” class.
      • Create a reference to front.
      • Performs “while” loop. This loop will repeat to obtain last node.
        • Compute the value of next node by calling “getNextNode()” method.
      • Set the new node at last of the queue by calling “setNextNode()” method.
        • • If the queue is empty, then
            • Assign the next node to “null” by using “QueueNode” class.
            • Increment the number of items.
  • Define the method “removeFromQueue()”.
    • If the queue is not empty, then get the element at front node by calling “getQueueElement()” method and eliminate the front node.
      • Finally returns the resultant element.
        • • If the queue is empty, then returns null.
  • Define the method “isEmpty()”.
    • This method returns “true” if the value of “count” is equal to “0”. Otherwise, returns “false”.
  • Define the method “displayQueueValues()”.
    • Create a reference to front.
    • Performs “while” loop. This loop will repeat to display all elements in queue.
      • Display the element of the queue.
      • Go to the next node by using “getNextNode()” method.

Filename: “QueueNode.java”

• Define “QueueNode” class.
  • Declare required variables for queue elements and next node value.
  • Create default constructor for “QueueNode” class.
    • Assign “null” values for queue elements and next node.
  • Create the parameterized constructor for “QueueNode” class.
  • Define the method “setNextNode()” which is used to set value for next node.
  • Define the method “getNextNode()” which is used to returns the next node value.
  • Define the method “setQueueElement()” which is used to assign value for queue elements.
  • Define the method “getQueueElement()” which is used to returns queue elements.

Filename: “LinkedQueueTest.java”

• Define “LinkedQueueTest” class.
  • Define main function.
    • Create an object “nameQueue” for “LinkedQueue” class.
    • Add names to object “nameQueue” by using “addToQueue()” method.
    • Call the method “displayQueueValues()” to display the elements in queue.
    • Remove an element from the queue by calling the method “removeFromQueue()”.
    • Display the result of whether the queue is empty or not by calling the method “isEmpty()”.
    • Display the elements in queue after removing an element from queue by calling the method “displayQueueValues()”.
    • Remove the elements from the queue by calling the method “removeFromQueue()”.
    • Display the result of whether the queue is empty or not by calling the method “isEmpty()”.