1.來源:java8技術手冊

2.問題描述:
當運行程式時，結果為下列程式碼，程式該如何修改才能得到字串形式的結果?
My hand is CardGame.Card@6d06d69c CardGame.Card@7852e922 CardGame.Card@4e25154f CardGame.Card@70dea4e CardGame.Card@5c647e05+

Your hand is CardGame.Card@33909752 CardGame.Card@55f96302 CardGame.Card@3d4eac69 CardGame.Card@42a57993 CardGame.Card@75b84c92+
3. ** 附上6段程式碼**
3-1.

public enum Suit {
	CLUBS, DIAMONDS, HEARTS, SPADES
}

3-2.public enum Rank { TWO, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING, ACE }
3-3.

public class Card implements Comparable<Card>{
	private Suit suit;
	private Rank rank;
	public Card(Rank rank, Suit suit) {
		this.rank = rank;
		this.suit = suit;
	}
	@Override
	public int compareTo(Card card) {
		if(suit.equals(card.suit)) {
			if(rank.equals(card.rank)) {
				return 0;
			}
			return rank.compareTo(card.rank)<0 ? -1 : 1;
		}else {
			return suit.compareTo(card.suit)<0 ? -1 : 1;
		}
	}
	public String toSring() {
		return rank + " of " + suit;	}
}

3-4.

public class Hand {
	private Vector<Card> hand = new Vector<Card>();
	
	public void add(Card card) {
		hand.add(card);
	}
	public Hand sort() {
		Collections.sort(hand);
		return this;
	}
	public String toString() {
		StringBuilder str = new StringBuilder();
		for(Card card : hand) {
			str.append(" " +card);
		}
		return str.toString();
	}
}

3-5.

public class CardDeck {
	public CardDeck() {
		for(Suit suit : Suit.values())
			for(Rank rank : Rank.values())
				deck.push(new Card(rank, suit));
	}
	public Hand dealHand(int numCards) {
		Hand hand = new Hand();
		for(int i = 0; i<numCards; i++) {
			hand.add((Card)deck.pop());
		}
		return hand;
	}
	public void shuffle() {
		Collections.shuffle(deck);
	}
	private Stack<Card> deck = new Stack<Card>();
}

3-6.

class TryDeal {
	public static void main(String[] args) {
		CardDeck deck = new CardDeck();
		deck.shuffle();
		Hand myHand = deck.dealHand(5).sort();
		Hand yourHand = deck.dealHand(5).sort();
		System.out.println("\nMy hand is" + myHand);
		System.out.println("\nYour hand is" + yourHand);
	}
}