1. Comparing ArrayLists and Arrays

2. ArrayLists ArrayLists are one type of flexible-size collection classes supported by Java –ArrayLists increase and decrease capacity as necessary. Flexible-size collections such as ArrayLists can only store objects, not primitive data type values To use ArrayLists, you need to import the ArrayList class: import java.util.ArrayList; Declaring and instantiating an ArrayList: ArrayList hand; hand = new ArrayList ();

3. ArrayLists Use the add method to add elements to an ArrayList: hand.add(new Card(“Spades”, “Ace”)); Use the remove method to remove elements from an ArrayList: int index = 0; hand.remove(index); Use the size method of an ArrayList to find its size: int index = 0; while(index < hand.size())

4. Accessing ArrayList Elements Accessing ArrayList elements using a for each loop: for(Card cardObject: hand) { System.out.println(cardObject.getFace()) } Accessing ArrayList elements using the Iterator object and the Iterator object’s hasNext and next methods: Iterator it = hand.iterator(); while(it.hasNext()) { Card cardObject = it.next(); System.out.println(cardObject.getFace()); }

5. Accessing ArrayList Elements Accessing ArrayList elements using a while loop, an index and the ArrayList get method: int index = 0; while(index < hand.size()) { Card cardObject = hand.get(index); System.out.println(cardObject.getFace()); index++; } Accessing ArrayList elements using a for loop, an index and the ArrayList get method: for(int index = 0; index < hand.size(); index++) { Card cardObject = hand.get(index); System.out.println(cardObject.getFace()); } Using no local variable: for(int index = 0; index < hand.size(); index++) { System.out.println(hand.get(index).getFace()); }

6. Arrays Arrays are a named, fixed size, set of variables. Arrays can store objects or primitive-type values. Declaring and instantiating an Array object: Card[] deck; deck = new Card[52]; boolean[] available = new boolean[52]; Notice that when an Array is declared you know what type of data it will hold. When the Array is instantiated, the size is set.

7. Arrays Arrays can be created and assigned values in one statement: double[] prices = {14.95, 12.95, 11.95, 9.95}; int[] values = {3, 5, 7, 9}; boolean[] responses = {true, false, true, true, false}; String[] bookCodes = {"warp", "mbdk", "citr"}; Book[] books = {new Book("warp"), new Book("mbdk")}; String[] suits = {"Spades","Hearts","Clubs","Diamonds"};

8. Arrays Access an array element using the element’s index inside square brackets Assign values to Array elements The Array length field contains the size of the array. boolean[] available = new boolean[50]; for(int index = 0; index < available.length; index++) { available[index] = true; } String[] suits = {"Spades", "Hearts", "Clubs", "Diamonds"}; String[] faces = {"Ace","2","3","4","5","6","7","8","9","10", "Jack","Queen","King"}; Card[] deck = new Card[52]; for(int index = 0; index < deck.length; index++) { deck[index] = new Card(suits[index/13], faces[index%13]); }