使用链表实现队列

Question

In this queue implementation example, i am not able to understand what is inside the class Node ie Node next. is it the same Node class object that we are currently in or some other class. how is deletefirst() removing the first element?

    import java.io.*;
    class Node
    {
       public int data;
       public Node next;
       public Node(int x)
       {
         data=x;
       }
       public void displayNode()
       {
         System.out.print(data+"  ");
       }
    }
    class LinkList
    {
      

 private Node first;
   private Node last;
   public LinkList()
   {
     first=null;
     last=null;
   }
   public void insertLast(int x)
   {
     Node newNode=new Node(x);
     newNode.next=null;
     if(isEmpty())
       first=newNode;
     else
       last.next=newNode;
     last=newNode;
   }
   public int deleteFirst()
   {
     int t=first.data;
     if(first.next==null)
       last=null;
     first=first.next;
     return t;
   }
   public int peekFirst()
   {
     return(first.data);
   }
   public boolean isEmpty()
   {
     return(first==null);
   }
   public void displayList()
   {
     Node current=first;
     while(current!=null)
     {
       current.displayNode();
       current=current.next;
     }
   }
   }

Answer 1

It removes the element by moving its pointer to the next node in the Queue

public int deleteFirst()
{
  int t=first.data; // Gets data from first Node.
  if(first.next==null) // Checks if next element is null. If true. Queue is empty so last element is null
    last=null;
  first=first.next; // Sets first to the next Node. <== This is where your magic happens.
  return t; // Returns the removed item from your Queue
}