数据结构之栈

public class MyStack<T> {
        private Object[] data;
        private int      top;
        private MyStack(){
            data = new Object[100];
            top = -1;
        }
        public synchronized void  put(T t) {
            top++;
            data[top]=t;
        }
        public synchronized T pop() {
            if(top<0) {
                return null;
            }
            T t = (T) data[top];
            top --;
            return t;
        }
}