package week1.com.coding.basic;
/**
* ջ���������Ƚ����
*
* @author Administrator
*
*/
public class Stack
{
private ArrayList elementData = new ArrayList();
int size;
/** ÿ���ƽ�����������ƽ� **/
public void push(Object o)
{
if (o == null)
{
throw new RuntimeException("�ƽ�Ԫ�ز���Ϊ��");
}
elementData.add(o);
size++;
}
public Object pop()
{
// ÿ�δ����
if (size ==0)
{
throw new RuntimeException("��ջ��û�пɵ���Ԫ��");
}
Object object = elementData.get(--size);
return object;
}
public Object peek()
{
return null;
}
public boolean isEmpty()
{
return elementData.size() == 0;
}
public int size()
{
return elementData.size();
}
}