Challenge 3
Generics and Collections
/**
* Implementation of a Double Linked List; forward and backward links point to adjacent Nodes.
*
*/
public class LinkedList<T>
{
private T data;
private LinkedList<T> prevNode, nextNode;
/**
* Constructs a new element
*
* @param data, data of object
* @param node, previous node
*/
public LinkedList(T data, LinkedList<T> node)
{
this.setData(data);
this.setPrevNode(node);
this.setNextNode(null);
}
/**
* Clone an object,
*
* @param node object to clone
*/
public LinkedList(LinkedList<T> node)
{
this.setData(node.data);
this.setPrevNode(node.prevNode);
this.setNextNode(node.nextNode);
}
/**
* Setter for T data in DoubleLinkedNode object
*
* @param data, update data of object
*/
public void setData(T data)
{
this.data = data;
}
/**
* Returns T data for this element
*
* @return data associated with object
*/
public T getData()
{
return this.data;
}
/**
* Setter for prevNode in DoubleLinkedNode object
*
* @param node, prevNode to current Object
*/
public void setPrevNode(LinkedList<T> node)
{
this.prevNode = node;
}
/**
* Setter for nextNode in DoubleLinkedNode object
*
* @param node, nextNode to current Object
*/
public void setNextNode(LinkedList<T> node)
{
this.nextNode = node;
}
/**
* Returns reference to previous object in list
*
* @return the previous object in the list
*/
public LinkedList<T> getPrevious()
{
return this.prevNode;
}
/**
* Returns reference to next object in list
*
* @return the next object in the list
*/
public LinkedList<T> getNext()
{
return this.nextNode;
}
}
/**
* Queue Iterator
*
* 1. "has a" current reference in Queue
* 2. supports iterable required methods for next that returns a generic T Object
*/
class QueueIterator<T> implements Iterator<T> {
LinkedList<T> current; // current element in iteration
// QueueIterator is pointed to the head of the list for iteration
public QueueIterator(LinkedList<T> head) {
current = head;
}
// hasNext informs if next element exists
public boolean hasNext() {
return current != null;
}
// next returns data object and advances to next position in queue
public T next() {
T data = current.getData();
current = current.getNext();
return data;
}
}
/**
* Queue: custom implementation
* @author John Mortensen
*
* 1. Uses custom LinkedList of Generic type T
* 2. Implements Iterable
* 3. "has a" LinkedList for head and tail
*/
public class Queue<T> implements Iterable<T> {
LinkedList<T> head = null, tail = null;
/**
* Add a new object at the end of the Queue,
*
* @param data, is the data to be inserted in the Queue.
*/
public void add(T data) {
// add new object to end of Queue
LinkedList<T> tail = new LinkedList<>(data, null);
if (this.head == null) // initial condition
this.head = this.tail = tail;
else { // nodes in queue
this.tail.setNextNode(tail); // current tail points to new tail
this.tail = tail; // update tail
}
}
/**
* Returns the data of head.
*
* @return data, the dequeued data
*/
public T delete() {
T data = this.peek();
if (this.tail != null) { // initial condition
this.head = this.head.getNext(); // current tail points to new tail
if (this.head != null) {
this.head.setPrevNode(tail);
}
}
return data;
}
/**
* Get the number of elements in the Queue.
*/
public int size() {
int count = 0;
for (T data : this) {
count++;
}
return count;
}
/*
* Returns true if Queue is empty.
*/
public boolean isEmpty() {
return this.head == null;
}
/**
* Return data in Queue.
*/
public String toString() {
String str = "";
for (T data : this) {
str += data + " ";
}
return str;
}
/**
* Returns data as List.
*/
public List<T> asList() {
List<T> list = new ArrayList<>();
for (T data : this) {
list.add(data);
}
return list;
}
/**
* Returns the data of head.
*
* @return this.head.getData(), the head data in Queue.
*/
public T peek() {
return this.head.getData();
}
/**
* Returns the head object.
*
* @return this.head, the head object in Queue.
*/
public LinkedList<T> getHead() {
return this.head;
}
/**
* Returns the tail object.
*
* @return this.tail, the last object in Queue
*/
public LinkedList<T> getTail() {
return this.tail;
}
/**
* Returns the iterator object.
*
* @return this, instance of object
*/
public Iterator<T> iterator() {
return new QueueIterator<>(this.head);
}
}
/**
* Queue Manager
* 1. "has a" Queue
* 2. support management of Queue tasks (aka: titling, adding a list, printing)
*/
class QueueManager<T> {
// queue data
private final String name; // name of queue
private int count = 0; // number of objects in queue
public final Queue<T> queue = new Queue<>(); // queue object
/**
* Queue constructor
* Title with empty queue
*/
public QueueManager(String name) {
this.name = name;
}
/**
* Queue constructor
* Title with series of Arrays of Objects
*/
public QueueManager(String name, T[]... seriesOfObjects) {
this.name = name;
this.addList(seriesOfObjects);
}
/**
* Add an element to queue
*/
public void add(T data) {
System.out.println("Enqueued data: " + data);
this.queue.add(data);
this.count++;
}
/**
* Add a list of objects to queue
*/
public void addList(T[]... seriesOfObjects) { //accepts multiple generic T lists
for (T[] objects: seriesOfObjects)
for (T data : objects) {
this.queue.add(data);
this.count++;
}
}
/**
* Delete an element from queue
*/
public void delete() {
// print data else print null
System.out.println("Dequeued data: " + this.queue.delete());
this.count--;
}
/**
* Print any array objects from queue
*/
public void printQueue() {
System.out.print(this.name + " count: " + count + "\n" + "Data: ");
for (T data : queue)
System.out.print(data + " ");
System.out.println();
}
}
public class ShuffleQueue {
public static QueueManager<Object> shuffle(QueueManager<Object> q) {
// convert the QueueManager to an ArrayList
List<Object> list = new ArrayList<Object>(q.queue.asList());
// Shuffle the ArrayList
Collections.shuffle(list);
// creating a new QueueManager with the shuffled elements
QueueManager<Object> shuffled = new QueueManager<Object>("Shuffled");
shuffled.addList(list.toArray());
return shuffled;
}
public static void main(String[] args) {
// array of integers
Object[] numbers = new Integer[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
// creating a QueueManager with the integers
QueueManager<Object> q = new QueueManager<Object>("Numbers", numbers);
q.printQueue();
QueueManager<Object> shuffled = shuffle(q);
shuffled.printQueue();
// array of strings
Object[] words = new String[] { "Ephemeral" };
// creating a QueueManager with the string array
QueueManager<Object> qw = new QueueManager<Object>("Words", words);
qw.add("Serendipity");
qw.add("Quixotic");
qw.add("Melancholy");
qw.add("Perfidious");
qw.printQueue();
// shuffling the queue and store the result in a new QueueManager
QueueManager<Object> shuffledwords = shuffle(qw);
shuffledwords.printQueue();
}
}
ShuffleQueue.main(null);