Simple singly linked list in Java

Question

The list is pretty simple, here is my code:
ILinkedList.java

package datastructures;
public interface ILinkedList<T> {
 public enum posForOperation { BEGGINIG,BEFORE ,AFTER ,END }
 public class Node<T>{
 T data;
 Node next;
 public Node(T data){
 this.data = data;
 this.next = null;
 }
 }
 public Node newNode(T data);
 public void add(posForOperation insert_at, T data);
 public void add(posForOperation insert_at, T data, Node node);
 public void delete(posForOperation delete_at);
 public void delete(posForOperation delete_at, Node node);
 public void deleteAtPos(int pos);
 public Node search(T data);
 public void print(); // for debugging
}

LinkedList.java

package datastructures;
public class LinkedList<T> implements ILinkedList<T> {
 private Node head;
 private Node end;
 public LinkedList(T data){
 Node new_node = new Node(data);
 head = new_node;
 end = new_node;
 }
 @Override
 public Node newNode(T data) {
 return new Node(data);
 }
 @Override
 public void add(ILinkedList.posForOperation insert_at, T data) {
 Node new_node = newNode(data);
 if(insert_at == ILinkedList.posForOperation.BEGGINIG){
 new_node.next = head;
 head = new_node;
 }
 else if(insert_at == ILinkedList.posForOperation.END){
 end.next = new_node;
 end = new_node;
 }
 }
 @Override
 public void add(ILinkedList.posForOperation insert_at, T data, Node node) {
 if(insert_at == ILinkedList.posForOperation.BEFORE){
 Node tmp = head; 
 while(tmp.next != node && tmp.next != null){
 tmp = tmp.next;
 }
 Node new_node = newNode(data);
 new_node.next = node;
 tmp.next = new_node;
 }
 else if(insert_at == ILinkedList.posForOperation.AFTER){
 Node new_node = newNode(data);
 new_node.next = node.next.next;
 node.next = new_node;
 }
 else // in case of misuse
 add(insert_at, data);
 }
 @Override
 public void delete(ILinkedList.posForOperation delete_at) {
 if(delete_at == ILinkedList.posForOperation.BEGGINIG){
 head = head.next;
 }
 if(delete_at == ILinkedList.posForOperation.END){
 Node tmp = head;
 while(tmp.next != end && tmp != end){ // the second condition is in case that head = end
 tmp = tmp.next;
 }
 tmp.next = null;
 end = tmp;
 }
 }
 @Override
 public void delete(ILinkedList.posForOperation delete_at, ILinkedList.Node node) {
 if(node.next == null)
 delete(ILinkedList.posForOperation.END);
 else if(delete_at == ILinkedList.posForOperation.AFTER){
 node.next = node.next.next;
 }
 else if(delete_at == ILinkedList.posForOperation.BEFORE){
 Node tmp = head;
 while(tmp.next != node){
 tmp = tmp.next;
 }
 tmp.next = node.next;
 }
 else //in case of misuse
 delete(delete_at);
 }
 @Override
 public ILinkedList.Node search(T data) {
 Node tmp = head;
 while(tmp.data != data && tmp != null){
 tmp = tmp.next;
 }
 return tmp;
 }
 @Override
 public void deleteAtPos(int pos) {
 Node tmp = head;
 for (int i = 0; i < pos-1 && tmp != null; i++){
 tmp = tmp.next;
 }
 delete(ILinkedList.posForOperation.AFTER, tmp);
 }
 @Override
 public void print() {
 Node tmp = head;
 while(tmp != end){
 System.out.println(tmp.data);
 tmp = tmp.next;
 }
 }
}

• David: Not a review, but you spelt beginning incorrectly.
• rdllopes: There is no reason for ILinkedList name. You could just call List.

Answer 1

Initial impressions:

• public Node newNode(T data) shouldn't be on the interface, why would anything outside of the list need to construct one?
• print shouldn't be on the interface, I know you say it's for debugging, but a better approach would be to provider an iterator so that something outside the list could iterate the items and print them.
• I don't like the fact that Node is visible outside of the list class. It reveals too much of the underlying functionality. What happens if I call 'newNode' then pass the contents of it to the delete method?

• One of your delete methods takes in a 'delete_at' parameter, then ignores it in certain conditions and deletes the last member of the list instead...

  public void delete(ILinkedList.posForOperation delete_at, ILinkedList.Node node) {
   if(node.next == null)
   delete(ILinkedList.posForOperation.END);
   else if(delete_at == ILinkedList.posForOperation.AFTER){
  

• void deleteAtPos(int pos), there's no way for a caller to really know where in the list an item is (unless they count as they insert them?), so what's the purpose of this method?