USING JAVA -- add an addLast method to the following program (below). This metho

Question

USING JAVA -- add an addLast method to the following program(below). This method should create a new node for the integer data it is passed and add it to the end of the linked list. On each call of addLast, get the pointer to the last node by traversing the list from the first node to the last node. Then, using this pointer, attach the new node to the end of the list. Test your new method.

class MyLinkedListH1  
{
   private class Node            // inner class
   {
      private Node link;
      private int x;
   }
   //----------------------------------
   private Node first = null;    // initial value is null
   //----------------------------------
   public void addFirst(int d)
   {
      Node newNode = new Node(); // create new node
      newNode.x = d;             // init data field in new node
      newNode.link = first;      // new node points to first node
      first = newNode;           // first now points to new node
   }
   //----------------------------------
   public void traverse()
   {
      Node p = first;
      while (p != null)            // do loop until p goes null
      {
         System.out.println(p.x); // display data
         p = p.link;               // move p to next node
      }
   }
}
//==============================================
class C15h1
{
   public static void main(String[] args)
   {
      MyLinkedListH1 list = new MyLinkedListH1();
      list.addFirst(1);
      list.addFirst(2);
      list.addFirst(3);
      System.out.println("Numbers on list");
      list.traverse();
   }
}

Explanation / Answer

class MyLinkedListH1
{
private class Node // inner class
{
private Node link;
private int x;
}
class Node {
Object data;
Node next;
Node(Object d,Node n) {
data = d ;
next = n ;
}

public static Node addLast(Node header, Object x) {
// save the reference to the header so we can return it.
Node ret = header;

// check base case, header is null.
if (header == null) {
return new Node(x, null);
}

// loop until we find the end of the list
while ((header.next != null)) {
header = header.next;
}

// set the new node to the Object x, next will be null.
header.next = new Node(x, null);
return ret;
}
}
  
public void addFirst(int d)
{
Node newNode = new Node(); // create new node
newNode.x = d; // init data field in new node
newNode.link = first; // new node points to first node
first = newNode; // first now points to new node
}

public void traverse()
{
Node p = first;
while (p != null) // do loop until p goes null
{
System.out.println(p.x); // display data
p = p.link; // move p to next node
}
}
}
class C15h1
{
public static void main(String[] args)
{
MyLinkedListH1 list = new MyLinkedListH1();
list.addFirst(1);
list.addFirst(2);
list.addFirst(3);
System.out.println("Numbers on list");
list.traverse();
}
}

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