// get the last value in the list
  // or return null
  public E getLast() 
  {
    if ( isEmpty() )
      return null;   
    
    GenericNode<E> p = headPtr;
    while ( p.getNext() != null )
      p =  p.getNext();
    
    return p.getValue();
  } 

Testing Program

Of course, the program should be tested:

public class GenericLinkedListTester
{
  public static void main( String[] args )
  {
    // create an empty generic linked list
    GenericLinkedList<Integer> list = new GenericLinkedList<>(); 
    
    // insert some integers (autoboxed)
    list.insertFirst( 4 );
    list.insertFirst( 3 );
    list.insertFirst( 2 );
    list.insertFirst( 1 );
   
    list.traverse();
    System.out.println("\n"); 
    
    // test getFirst()
    System.out.println("First: " + list.getFirst() );
    list.deleteFirst();
    list.traverse();
    System.out.println("\n"); 
    System.out.println("New First: " + list.getFirst() );
      
    // test getLast()
    System.out.println("Last : " + list.getLast() );
 
  }
}

PS C:\Code> javac GenericLinkedListTester.java
PS C:\Code> java GenericLinkedListTester
1 2 3 4

First: 1
2 3 4

New First: 2
Last : 4
PS C:\CAI\java9Lessons\chap133\Private>

Seems to work. Industrial-grade testing would be much more thorough, though.