package Stack.src;

import java.util.Iterator;

/**

* 使用链表实现的栈

*/

public class ListStack<Item> implements MyStack<Item> {

private Node top = null;

private int N = 0;

private class Node {

Item item;

Node next;

}

@Override

public MyStack<Item> push(Item item) {

Node newTop = new Node();

newTop.item = item;

newTop.next = top;

top = newTop;

N++;

return this;

}

@Override

public Item pop() throws Exception {

if (isEmpty()) {

throw new Exception("stack is empty");

}

Item item = top.item;

top = top.next;

N--;

return item;

}

@Override

public boolean isEmpty() {

return N == 0;

}

@Override

public int size() {

return N;

}

@Override

public Iterator<Item> iterator() {

return new Iterator<Item>() {

private Node cur = top;

@Override

public boolean hasNext() {

return cur != null;

}

@Override

public Item next() {

Item item = cur.item;

cur = cur.next;

return item;

}

};

}

}