爲Stack鏈表添加delete方法（1.3.20）

package 數據結構.stack;

import java.util.Iterator;

public class StackNode<Item> implements Iterable {
    Node first;
    int N=0;
    private class Node{
        Item item;
        Node next;
    }
    public boolean isEmpty(){
        return N==0;
    }
    public int size(){
        return N;
    }
    public void push(Item item){
        Node oldfirst = first;
        first=new Node();
        first.item=item;
        first.next=oldfirst;
        N++;
    }
    public Item pop(){
        Item item=first.item;
        first=first.next;
        N--;
        return item;
    }
    //按照放入順序來計算k。
    public void delete(int k){
        Node temp = first;
        boolean delete=false;
        if (k==N){
            first=first.next;
            N--;
            delete=true;
        }else if (k>0&&k<N){
          //如果是Queue需要調整for循環並k-1。
            for (int i = N-1; i > 0; i--) {
                temp = temp.next;
                if (i == k+1 ) {
                    temp.next = temp.next.next;
                    delete=true;
                    N--;
                    break;
                }
            }
        } else{
            System.out.println("不存在第"+k+"個元素");
        }
        if (delete) System.out.println("刪除成功");
    }
    public Iterator iterator() {
        return new StackNodeIterator();
    }
    private class StackNodeIterator<Item> implements Iterator<Item> {
        Node oldFirst=first;
        int j=N;
        @Override
        public boolean hasNext() {
            return j>0;
        }

        @Override
        public Item next() {
            Item item=(Item) oldFirst.item;
            oldFirst= oldFirst.next;
            j--;
            return item;
        }

        @Override
        public void remove() {

        }
    }

}