java - Implementation of a Generic Singly Linked List -

new site. trying implement generic singlylinkedlist, fetch returns null though there nodes in , delete method return false, when true expected. in addition, functions fine when decide delete in reverse order. looking set of fresh eyes see missing. thanks-in-advance.

public class singlylinkedlist<t> {      private node<t> h;  // list header      public singlylinkedlist() {         h = new <t> node();  // dummy node         h.l = null;         h.next = null;     }      public boolean insert(t newnode) {         node n = new node();         genericnode node = (genericnode) newnode;         if (node == null) // out of memory         {             return false;         } else {             n.next = h.next;             h.next = n;             n.l = (t) node.deepcopy();             return true;         }     }      public genericnode fetch(object targetkey) {         node p = h.next;         genericnode node = (genericnode) p.l; // think there problem. right?          while (p != null && !(node.compareto(targetkey) == 0)) {             p = p.next;         }         if (p != null) {             return node.deepcopy();         } else {             return null;         }     }      public boolean delete(object targetkey) {         node q = h;         node p = h.next;         genericnode node = (genericnode)p.l;// think problem         while (p != null && !(node.compareto(targetkey) == 0)) {             q = p;             p = p.next;         }         if (p != null) {             q.next = p.next;             return true;         } else {             return false;         }     }      public boolean update(object targetkey, t newnode) {         if (delete(targetkey) == false) {             return false;         } else if (insert(newnode) == false) {             return false;         }         return true;     }      public void showall() {         node p = h.next;         while (p != null) //continue traverse list         {             system.out.println(p.l.tostring());             p = p.next;         }     }      /**      *      * @param <t>      */     public class node <t> {          private t l;         private node <t> next;          public <t> node() {         }     }// end of inner class node     } //end singlylinkedlist outer class 

the problem lies here (in fetch method):

    genericnode node = (genericnode) p.l; // think there problem. right?      while (p != null && !(node.compareto(targetkey) == 0)) {         p = p.next;     } 

you assing node only before entering loop, , change p value inside loop, node keeps initial value throughout whole loop. should use:

    genericnode node = null;      // define node before loop in order use later     while (p != null) {         node = (genericnode) p.l; // reset node value on each iteration         if (node.compareto(targetkey) == 0) {             break;         }         p = p.next;     } 

as have same code in delete, same fix apply...