title: "Cannot find this symbol" error while implementing double ended link list
body: <pre><code>class Link {
      public int data;
      public Link next;
  
      public Link(int d) {
          data = d;
      }
  
      public void displayLink() {
          System.out.println(data + "");
      }
  }
  
  class firstlastList {
      private Link first;
      private Link last;
  
      public firstlastList() {
          first = null;
          last = null;
      }
  
      public boolean isEmpty() {
          return first == null;
      }
  
      public void insertfirst(int dd) {
          Link newLink = new Link(dd);
          if (isEmpty())
              last = newLink;
          newLink.next = first;
          first = newLink;
      }
  
      public void insertLast(int dd) {
          Link newLink = new Link(dd);
          if (isEmpty())
              first = newLink;
          else
              last.next = newLink;
          last = newLink;
      }
  
      public long deletefirst() {
          long temp = first.data;
          if (first.next == null)
              last = null;
          first = first.next;
          return temp;
      }
  
      public void displayList() {
          System.out.println("List(first--&gt;last)");
          Link current = first;
          while (current != null) {
              current.displayLink();
              current = current.next;
          }
          System.out.println("");
      }
  }
  
  class FirstLastApp {
  
      public static void main(String args[]) {
          FirstLastApp theList = new FirstLastApp();
          theList.insertfirst(10);
          theList.insertfirst(98);
          theList.insertfirst(112);
          theList.insertLast(123);
          theList.insertLast(75);
          theList.insertLast(12);
          theList.displayList();
          theList.deletefirst();
          theList.deletefirst();
          theList.displayList();
      }
  }
  </code></pre>