public class PKListDemo {

   static class Item<T> {

      T key;

      Item next;

      Item prev;

​

      // Konstruktor

      Item(T k, Item p) {

         key = k;

         next = p;

         prev = null;

      }

   }

  static class PKList<T> {

     public Item head;

     // Konstruktor

     public PKList() {

       head = null;

     }

     public boolean isEmpty() {

       return (head == null);

     }

     public Item search (T k) {

       Item x = head;

       while (x != null && x.key != k) {

         x = x.next;

       }

       return x;

     }

     public Item insert (T k) {

       Item x = new Item<T>(k, head);

       if (head != null) {

         head.prev = x;

       }

       head = x;

       return x;

     }

     public void delete (Item k) {

       if (k.prev == null) {

         // k ist head

         head = k.next;

       } else {

         // k.prev != null

         k.prev.next = k.next;

       }

       if (k.next != null) {

         k.next.prev = k.prev;

       }

     }

  }

   public static void main(String[] args) {

      int[] A = {4, 8, 15, 16, 23, 42};

      PKList<Integer> list = new PKList<>();

      for (int i = 0; i < A.length; i++) {

        list.insert(A[i]);

      }

      Item item = list.search(16);

      list.delete(item);

   }  

}