linked list - How to implement CircularLinkedList in Java without first & Last? -

a question in linkedlists book asks implement linkedlist without first , last pointers while allowing access list "current" pointer. not quite sure on right track, appreciated. here tried, insert/delete working...

class link  {     public int idata;                   public link next;                 public link(int id) // constructor  {   idata = id;                            }                            public void displaylink()      {  system.out.print(idata + " "); } }  // end class link   public class circularlinkedlist { private link current;         private link first;  //------------------------------------------------------------- public circularlinkedlist(){  current = null;  }  public circularlinkedlist(link link){ current = link; }  public link getcurrent(){ return current; }  public link getnext(){ return current.next; }  public void setcurrent(link current){ this.current = current; }  public void insert(int data){ link newlink = new link(data);  //only link if(current == null){      current = newlink;     first = current; }else{     current.next = newlink; }  newlink.next = first; }  public void delete(){  }  public int find(int key){ return -1; }   public void displaylist() { link tmp = current; while(current != null)      // until end of list,   {      current.displaylink();   // print data      current = current.next;  // move next link      if(current == tmp)          break;   }   system.out.println(""); }  public static void main(string ...args){ circularlinkedlist list = new circularlinkedlist(); list.insert(10); list.insert(20); list.insert(30); list.insert(40);  list.displaylist(); }   } 

your link class needs set next value in constructor

public link (int id, link next) 

then want list circular first link, next itself. when insert element a, make current.next a, , a.next previous value of current.next. delete id search until find (current.next in loop) , save previous element b each time. when find element searching set b.next b.next.next.