CareerCup

public class CircularArray {
	private int[] arr;
	private int size;
	private int capacity;
	private int startIndex;
	private int endIndex;
	
	public CircularArray(int size)
	{
		arr = new int[size];
		this.size = size;
		startIndex = 0;
		endIndex = 0;
		capacity = 0;
	}
	
	public boolean enqueue(int val)
	{
		if(capacity == size) return false;
		capacity++;
		arr[endIndex] = val;
		endIndex = (endIndex + 1) % size;
		return true;
	}
	
	public int dequeue() throws IllegalStateException
	{
		if(capacity == 0) throw new IllegalStateException("Queue is empty");
		capacity--;
		int idx = startIndex;
		startIndex = (startIndex + 1) % size;
		return arr[idx];
	}
}

If you want to get call from Groupon, write your own code. This will never help you out.

public class Queue {

private String[] array = null;
private int start = 0;
private int end = -1;
static private int currSize = 0;
static private boolean isDataAdded = false;
private int queueSize = 0;

public Queue(int size){
this.array = new String[size];
this.queueSize = size;
}

public synchronized void enQueue(String data) throws InterruptedException{
if(currSize >= this.queueSize){
System.out.println("queue is full to enQueue "+Thread.currentThread().getName()
+" is blocked till queue will get deQueue'd");
this.wait();
}else if(currSize <= this.queueSize){
this.end ++;
this.array[this.end] = data;
currSize ++;
isDataAdded = true;
System.out.println(data+" added to queue by "+Thread.currentThread().getName());
this.notify();
}
}

public synchronized String deQueue() throws InterruptedException {
String queueData = null;
if(currSize <= 0){
System.out.println("queue is empty to deQueue "+Thread.currentThread().getName()
+" is blocked till queue will get enQueue'd");
this.wait();
}else if(currSize > 0){
queueData = array[start];
array[start] = null;
if(isDataAdded){
this.end = ((this.start == 0) ? -1 : this.end);
isDataAdded = false;
}
this.start++;
currSize--;
if(this.start >= this.queueSize || currSize == 0){
this.start = 0;
this.end = -1;
}
this.notify();
System.out.println(queueData+" removed from queue by "+Thread.currentThread().getName());
}

return queueData;
}
}