CareerCup 14.6

Implement Circular Array

/*
 * Career Cup 14.6
 * 
 */

package CareerCup;

import java.util.Iterator;

public class CircularArray<T> implements Iterable<T> {
	private T items[];
	private int head;

	public CircularArray(int size) {
		items = (T[]) new Object[size];
		head = 0;
	}
	
	public int Size() {
		return items.length;
	}

	public void rotate(int rightShift) {
		if (rightShift < 0) {
			rightShift += items.length;
		}
		head = (head + rightShift) % items.length;
	}

	public int convert(int index) {
		int i = (index + head) % items.length;

		return i;
	}

	public T get(int index) {
		if (index < 0 || index >= items.length) {
			throw new java.lang.IndexOutOfBoundsException();
		}

		int i = convert(index);
		return items[i];
	}

	public void set(int index, T item) {
		int i = convert(index);
		items[i] = item;
	}

	@Override
	public Iterator<T> iterator() {
		return new CircularArrayIterator<T>(this);
	}

	private class CircularArrayIterator<TI> implements Iterator<TI> {
		private int current = -1; //current reflects the offset from the rotated head
		private TI[] refItems;
		
		public CircularArrayIterator(CircularArray<TI> c) {
			refItems = c.items;
		}
		
		@Override
		public boolean hasNext() {
			return current < refItems.length - 1;
		}

		@Override
		public TI next() {
			current++;
			int i = convert(current);
			return refItems[i];
		}

		@Override
		public void remove() {
			throw new UnsupportedOperationException();
		}

	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		CircularArray<Integer> arr;
		arr = new CircularArray<Integer>(5);
		for(int i = 0; i < arr.Size(); i++) {
			Integer in = new Integer(i + 10);
			arr.set(i, in);
		}
		
		System.out.println("Before rotate...");
		for(Integer i : arr) {
			System.out.println(i);
		}
		System.out.println("After rotated...");
		arr.rotate(2);
		for(Integer i : arr) {
			System.out.println(i);
		}
		
		
	}
}