import CITS2200.*;

        public class StackBlock implements Stack
        {
            int size;
            Object[] stackBlock;

            public StackBlock(int s){
               this.stackBlock = new Object[s];
                this.size = 0;
        }

        public boolean isEmpty(){
                if (this.size==0){
                    return true;
                    }
                    return false;
        }

        public boolean isFull(){
                if(this.size==this.stackBlock.length){
                    return true;
                }
                return false;
        }

        public void push(Object o){
                if(isFull()){
                    throw new Overflow("StackBlock is full");
                }
                else{
                    this.stackBlock[this.size] = o;
                    this.size++;
                }
        }

        public Object examine() {
            if (isEmpty()) {
                throw new Underflow("StackBlock is empty");
            } else {
                return this.stackBlock[this.size];

            }
        }

        public Object pop(){
            if (isEmpty()) {
                throw new Underflow("StackBlock is empty");
            } else {
                this.size--;
                return stackBlock[size];
            }
        }




        }