Simple Circular Queue

Queue.java

package com.operations.queue;

public class Queue{

	private int N ;
	private static final int SIZE = 1024;
	private int[] arr = null;
	private int t = 0;
	private int f = 0;

	public Queue(){
		this(SIZE);
	}

	public Queue(int N){
		this.N = N;
		this.arr = new int[this.N];
	}

	public int size(){
		return (this.N-f+t)%this.N; 
	}

	public boolean isEmpty(){
		return f==t;
	}

	public void offer(int x) throws QueueException{

		if(size()<this.N-1){
			this.arr[t] = x;
			t = (t+1)%this.N;
		}else{
			throw new QueueException("Error : Queue is full");
		}
	}

	public int poll() throws QueueException{
		if(!isEmpty()){
			int x = this.arr[f];
			f = (f+1)%this.N;
			return x;
		}else{
			throw new QueueException("Error : Queue is empty");
		}
	}
}

class QueueException extends RuntimeException{
	public QueueException(String message){
		super(message);
	}

}