Programming Fundamentals I Java Programming Spring 2007

1. Programming Fundamentals IJava ProgrammingSpring 2007 XuanTung Hoang tung_hx@icu.ac.kr Lecture No. 12

2. Encapsulation: Case Study CardGame Project

3. Creating Reusable Packages Package name. Your internet domain name • Add package declaration package ice0124.lib; class RNG { … … } Main code Package name and the directory are matched • Compile the source code with –d switch • javac –d <path> RNG.java • This will create directories: <path>/ice0124/lib • And class files inside the directory above

4. Using the package • Reuse classes in a package: • add import statement • Use fully qualified class name • Use javac with –classpath switch to specify the location of the package • javac –classpath <path_to_package> yourcls.java • To run a java main class (class with main method) also use -classpath • java -classpath <path_to_package>;<path_to_mainclass> yourcls

5. CardGame project: Game rules • 4 players • Each player has 13 random cards from a deck of cards • Play in rounds. In each round, each player submits 1 of his card and compares to cards from other players. The winner get 1 point, other get 0 point. • Card comparison: • King > Queen > Jack > Ten > … > Two > Ace • Heart > Diamond > Spades > Clubs • For example: Ace of Heart (1oH) > Ace of Diamond (1oD), 2oC > AoH • At the end of the game, the winner is the player whose score is highest.

6. CardGame: Analysis • List up all objects possibly existing in the game: • Card: Card class • Deck of cards: DeckOfCards class • Player: Player class • Game: GameControl class • Card class: represents a card • face and suit • DeckOfCards: represents a deck of cards • array of Card and related actions (deal and shuffle) • Player: represent player • Cards that a player has • Score that he gains • Submit a card to play in a round • GameControl: Represent a game • Game rules: card comparison, start a game and collaborate other objects according to a game rule

7. CardGame: Analysist Card DeckOfCards + faceDesc: String[] + suitDesc: String[] - face: int - suit: int + toString(): String - cards: Card[] - currentCard: int + shuffling(): void + deal(): Card Player GameControl • - name: String • - cards: Card[] • - currentCard: int • score: int • + incScore(inc:int ): void • + submit(): Card - deck: DeckOfCards - players: Player[] + compare(c1:Card, c2: Card) + prepare(): void + play(): void

8. GameControl • Constructor: • Create deck, and players • prepare() method: • shuffle the deck of cards • Deal cards to players • play() method: • while (game is not ended) • Ask each player to submit a card to play • Compare those cards to find biggest ones and the winner of this round • Increase score of the winner. • Display the winner

9. GameControl: • play() method: • How to compare cards? • If card1.face > card2.face  card1 > card2 • If (card1.face == card2.face) and (card1.suit > card2.suit)  card1 > card2 • The order of elements in faceDesc and suitDesc matters • How to find the winner in one round? • winner = player 0 • For i from 0 to 3 • Compare winner’s card with player i’s card. • If player i's card > winner’s card  winner = player i • How to find the final winner when game ends? • winner = player 0 • For i from 0 to 3 • Compare winner’s score with player i’s score. • If player i's score > winner’s score  winner = player i

10. What do you learn from this project? • How to use array • Scanning arrays with for loop • Array of string to store descriptions • Array index to compare strings • … • Group actions into methods • Object oriented programming is fun • Encapsulation is good • …. • …. • And the most important thing is … Make a plan before you actually write code!! Every line of code you write is for that plan!