Circular queue

Circular queue

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+package com.arman;
+
+import java.util.Arrays;
+
+public class CircularQueueImplementation {
+
+    public static void main(String[] args) {
+
+        CircularQueue<Integer> circularQueue = new CircularQueue(8);
+
+        circularQueue.enqueue(15);
+        circularQueue.enqueue(16);
+        circularQueue.enqueue(17);
+        circularQueue.enqueue(18);
+        circularQueue.enqueue(19);
+        circularQueue.enqueue(20);
+        circularQueue.enqueue(21);
+        circularQueue.enqueue(22);
+
+        System.out.println("Full Circular Queue" + circularQueue);
+
+        System.out.print("Dequeued following element from circular Queue ");
+        System.out.println(circularQueue.dequeue() + " ");
+        circularQueue.enqueue(23);
+        System.out.println("After enqueueing circular queue with element having value 23");
+        System.out.println(circularQueue);
+    }
+
+}
+
+//implementation of Circular Queue using Generics
+class CircularQueue<E> {
+
+    private int currentSize; //Current Circular Queue Size
+    private E[] circularQueueElements;
+    private int maxSize; //Circular Queue maximum size
+
+    private int rear;//rear position of Circular queue(new element enqueued at rear).
+    private int front; //front position of Circular queue(element will be dequeued from front).      
+
+    public CircularQueue(int maxSize) {
+        this.maxSize = maxSize;
+        circularQueueElements = (E[]) new Object[this.maxSize];
+        currentSize = 0;
+        front = -1;
+        rear = -1;
+    }
+
+    /**
+     * Enqueue elements to rear.
+     */
+    public void enqueue(E item) throws QueueFullException {
+        if (isFull()) {
+            throw new QueueFullException("Circular Queue is full. Element cannot be added");
+        }
+        else {
+            rear = (rear + 1) % circularQueueElements.length;
+            circularQueueElements[rear] = item;
+            currentSize++;
+
+            if (front == -1) {
+				front = rear;
+			}
+        }
+    }
+
+    /**
+     * Dequeue element from Front.
+     */
+    public E dequeue() throws QueueEmptyException {
+        E deQueuedElement;
+        if (isEmpty()) {
+            throw new QueueEmptyException("Circular Queue is empty. Element cannot be retrieved");
+        }
+        else {
+            deQueuedElement = circularQueueElements[front];
+            circularQueueElements[front] = null;
+            front = (front + 1) % circularQueueElements.length;
+            currentSize--;
+        }
+        return deQueuedElement;
+    }
+
+    /**
+     * Check if queue is full.
+     */
+    public boolean isFull() {
+        return (currentSize == circularQueueElements.length);
+    }
+
+    /**
+     * Check if Queue is empty.
+     */
+    public boolean isEmpty() {
+        return (currentSize == 0);
+    }
+
+    @Override
+    public String toString() {
+        return "CircularQueue [" + Arrays.toString(circularQueueElements) + "]";
+    }
+
+}
+
+class QueueFullException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public QueueFullException() {
+        super();
+    }
+
+    public QueueFullException(String message) {
+        super(message);
+    }
+
+}
+
+class QueueEmptyException extends RuntimeException {
+
+    private static final long serialVersionUID = 1L;
+
+    public QueueEmptyException() {
+        super();
+    }
+
+    public QueueEmptyException(String message) {
+        super(message);
+    }
+
+}