Help in the add method

Question

how can i implement the code in the add method, and how should i add a main method to print the list.
import java.util.*;
public class SinglyLinkedList implements List
  // an inner class: This is our node class, a singly linked node!
  private class Node
    Object data;
    Node next;
    Node(Object o, Node n)
      data = o;
      next = n;
    Node(Object o)
      this(o, null);
    Node( )
      this(null,null);
  private Node head; // the "dummy" head reference
  private int size;  // the number of items on the list
  public SinglyLinkedList()
    head = new Node(); // dummy header node!
  public void add(int index, Object o)
  //need some help here
  public boolean add(Object element)
       if (element == null) return false;
       // Check for dummy head node
       if (head.data == null)
            head = new Node(element, null);
    else
    // Traverse the list until we find the end
    Node next = head;
    while (next.next != null)
         next = next.next;
    next.next = new Node(element, null);
    return true;
public static void main (String[] args){
  //need some help here
}

Answer 1

you not need to implement List you can just use add methods of it cause
if you implementing it without implements all the methods in it then you
must declare you class as abstract class;
if you implemets List then your class should contains all the methods of interface List for example
import java.util.*;
public class SinglyLinkedList implements List
  // an inner class: This is our node class, a singly linked node!
  private class Node
    Object data;
    Node next;
    Node(Object o, Node n)
      data = o;
      next = n;
    Node(Object o)
      this(o, null);
    Node( )
      this(null,null);
  private Node head; // the "dummy" head reference
  private int size;  // the number of items on the list
  public SinglyLinkedList()
    head = new Node(); // dummy header node!
  public void add(int index, Object o)
    //need some help here
  public boolean add(Object element)
    if (element == null) return false;
    // Check for dummy head node
    if (head.data == null)
      head = new Node(element, null);
    else
      // Traverse the list until we find the end
      Node next = head;
      while (next.next != null)
        next = next.next;
      next.next = new Node(element, null);
    return true;
  public int size(){
  return 0;
  public boolean isEmpty(){
    return false;
  public boolean contains(Object o){
    return false;
  public Iterator iterator(){
    return null;
  public Object[] toArray(){
    return null;
  public Object[] toArray(Object a[]){
    return null;
  public  boolean remove(Object o){
    return false;
  public boolean containsAll(Collection c){
    return false;
  public  boolean addAll(Collection c){
    return false;
  public boolean addAll(int index, Collection c){
    return false;
  public boolean removeAll(Collection c){
    return false;
  public boolean retainAll(Collection c){
    return false;
  public void clear(){}
  public boolean equals(Object o){
    return false;
  public  int hashCode(){
    return 0;
  public Object get(int index){
    return null;
  public  Object set(int index, Object element){
    return null;
  public Object remove(int index){
    return null;
  public int indexOf(Object o){
    return 0;
  public int lastIndexOf(Object o){
    return 0;
  public ListIterator listIterator(){
    return null;
  public ListIterator listIterator(int index){
    return null;
  public List subList(int fromIndex, int toIndex){
    return null;
  public static void main (String[] args){
    //need some help here
}