Announcements

1
Announcements Review

• Last Time Collections
• ArrayList -
• look up - constant time
• remove, resizing, insert in the middle -
  expensive, time proportional to the list size
• Today a new collection
• Linked List - similar operations as ArrayList,
  but different storage model
• resizing, removal, insertion - constant time
• find - proportional to list size.

• Announcements
• Lab 9 Inheritance Defining using class
  hiearchies
• Read
• RS 11

2
Linked List Storage Model
start
end
null
next
prev
Key
node

• No diriect indexing, as in arrays, so you must
  iterate over the list to enumerate an element
• Adding at the front or the back is constant
  time, i.e., resizing is cheap

3
InterestingLinkedListltEgt Methods

• size() - returns number of objects
• add(Object o) - adds at end of list
• get(int i) - returns ith object in the list
• set(int i, Object o) - stores o at ith position
  in list
• add(int i, Object o) - adds o at ith position,
  shifts other objects to the right
• E remove() - removes and returns element current
  position, shifts elements to the left
• removeFirst(), removeLast(), remove(E v),
  remove(int i), remove()

4
InterestingLinkedListltEgt Methods

• E clone() - return a shallow copy of the list
• Boolean addAll(LinkedListltEgt c) - add collection
  c to end of list, return true if list changes
• E peek() - return the first element without
  removing it from the list
• Boolean hasNext(), E next() - iteration

5
Linked List
apples
null
33
41
8
14
101
McIntosh
Red
Gala
Golden Delicious
Fuji
Linked list example declaration (same as
ArrayList) LinkedListltItemsgt apples new
LinkedListltItemsgt() Items a new
Items(McIntosh, 33) apples.add(a) a new
Items(Red, 41) apples.add(a) ...
6
Iterators for LinkedList

• // Basic format
• IteratorltEgt itr list.iterator()
• while (itr.hasNext())
• E element itr.next() // do something with
  the object
• // Example Delete Gala apples inventory
• LinkedListltItemsgt apples new LinkedListltItemsgt()
  
• ...
• IteratorltItemsgt i apples.iterator()
• while (i.hasNext())
• Items item i.next()
• if (item.getName().equals(Gala))
• i.remove()

7
BlueJ