java FIFO

/**
 * 先进先出
 * 
 * @author 002040
 * 
 */
public class FIFO {

	Object[] buf;
	int first, next;
	int size, maxSize;

	public FIFO(int maxSize) {
		if (maxSize < 0)
			throw new IllegalArgumentException("参数不合法");
		this.maxSize = maxSize;
		buf = new Object[maxSize];
	}

	public void put(Object value) {
		if (!isFull()) {
			buf[next] = value;
			if (++next == maxSize)
				next = 0;
			size++;
		}
	}

	public Object get() {
		if (isEmpty())
			return null;
		Object t = buf[first];
		buf[first] = null;
		if (++first == maxSize)
			first = 0;
		size--;
		return t;
	}

	public boolean isEmpty() {
		return size == 0;
	}

	public boolean isFull() {
		return size == maxSize;
	}

	public static void main(String[] args) {
		FIFO fifo = new FIFO(2);
		fifo.put("a");
		fifo.put("b");
		System.out.println(fifo.get());
		System.out.println(fifo.get());
		System.out.println(fifo.get());
	}
}