Lecture 26

Linked Lists Continued

Node Inner Classes

• ListNode has no use or meaning apart from the linked list
• our existing definition opens the list to privacy leaks
• a careless application programmer could get a reference and change it
• make ListNode an inner class within the 'linked list' class
• advantages
  
• eliminates privacy leaks
• simplifies LinkedList
• disadvantages
• reduces flexibility

Example

public class LinkedList inner
{
private class ListNode // inner class
{
private myObject item;
private ListNode next;
public ListNode(MyObject item, ListNode next) { ... }
}
private listNode head; ...}

• using myObject as a generic
• linked lists with generics

public class LinkedList inner //good

{
private class ListNode /** this is good, but this alone does not suffice */
{
private T item;
private ListNode next; // bad
private ListNode next; //good

• use the generic type parameter firstly with the outer class as well as the inner class
• use the generic type parameter with every declaration of the generic object.