import java.util.Vector;

public class DataBuffer {
	private Vector al = new Vector();		//using vector

	Semaphore sem = new Semaphore(0);

	public void put(DataPacket p) {
		al.addElement(p);					//add elem
		sem.V();							//v
	}

	public DataPacket get() {
		sem.P();							//p
		DataPacket tem = (DataPacket) al.elementAt(0);//read elem
		al.removeElementAt(0);				//remove elem
		return tem;
	}

	public int size() {
		return al.size();
	}
}