栈_单链表实现

//链结点
public class Link {
    public long dData;
    public Link next;
    public Link(long dd) {
        dData=dd;    
    }
    public void displayLink() {
        System.out.print(dData+" ");
    }

}

public class LinkList {
        public Link first;
        public LinkList() {
            first=null;
        }
        //是否为空
        public boolean isEmpty() {
            return first==null;
        }
        //插入
        public void insertFirst(long dd) {
            Link newLink=new Link(dd);
            newLink.next=first;//插入头部，需要将next值为以前的first
            first=newLink;//改变frist为现在的插入
            
        }
        //删除头部
        public long deleteFirst() {
            Link temp=first;
            first=first.next;//改变头
            return temp.dData;
            
        }
        //遍历
        public void displayList() {
            Link current=first;
            while(current!=null) {
                current.displayLink();
                current=current.next;
            }
            System.out.println();
        }
        
    
}

public class LinkStack {
    private LinkList theList;
    public LinkStack() {
        theList=new LinkList();
    }
    public void push(long j) {
        theList.insertFirst(j);
    }
    public long pop() {
        return theList.deleteFirst();
    }
    public boolean isEmpty() {
        return theList.isEmpty();
    }
    public void displayStack() {
        System.out.print("Stack(top-->bottom):");
        theList.displayList();
    }

}

public class Test {

    public static void main(String[] args) {
        LinkStack theStack =new LinkStack();
        theStack.push(20);
        theStack.push(40);
        theStack.displayStack();
        theStack.push(60);
        theStack.push(80);
        theStack.displayStack();
        theStack.pop();
        theStack.pop();
        theStack.displayStack();
        
    }

}