java如何为deck类toString方法编写函数

Question

基本上，我有一个toString方法，可以显示已排序的卡片。基本上，如果我有一副完整的卡片，这就是输出的样子

{Ace of Clubs | Two of Clubs | Three of Clubs | Four of Clubs | Five of Clubs | Six of Clubs | Seven of Clubs | Eight of Clubs | Nine of Clubs | Ten of Clubs | Jack of Clubs | Queen of Clubs | King of Clubs | Ace of Diamonds | Two of Diamonds | Three of Diamonds | Four of Diamonds | Five of Diamonds | Six of Diamonds | Seven of Diamonds | Eight of Diamonds | Nine of Diamonds | Ten of Diamonds | Jack of Diamonds | Queen of Diamonds | King of Diamonds | Ace of Hearts | Two of Hearts | Three of Hearts | Four of Hearts | Five of Hearts | Six of Hearts | Seven of Hearts | Eight of Hearts | Nine of Hearts | Ten of Hearts | Jack of Hearts | Queen of Hearts | King of Hearts | Ace of Spades | Two of Spades | Three of Spades | Four of Spades | Five of Spades | Six of Spades | Seven of Spades | Eight of Spades | Nine of Spades | Ten of Spades | Jack of Spades | Queen of Spades | King of Spades}

目前，我通过一个简单的循环来实现这一点，它在开始处放置一个花括号，循环甲板中有多少元素，并添加甲板的输出。得到（我）。getCard（）+“|”。最后从结尾处减去三个字符，再加上一个大括号。但这不是一个非常花哨的解决方案，是非常有程序性的，我喜欢优雅的解决方案，我认为有一些函数可以达到这种目的，但我真的不知道lambda表达式或任何这样的，所以我想知道是否有人可以教我如何做到这一点。下面你会找到我目前的解决方案。感谢您的帮助，干杯

public String toString(){
        Collections.sort(deck);

        String result = "{";
        for(int i = 0; i < deck.size(); i++){
            result += deck.get(i).getCard() + " | ";
        }

        if(deck.size() == 0){
            return "{}";
        }

        result = result.substring(0, result.length() - 3);
        result += "}";

        shuffle();
        return result;
    } 

Answer 1

使用Java Lamda表达式，您可以用更少的代码和精力实现预期的结果。 比如：

public String toString(){
        Collections.sort(deck);
        String result = "{"+ deck.stream().map(element->element.getCard()).collect(Collectors.joining("|")) + "}";
        shuffle();
        return result;

    } 

Answer 2

根据MadProgammer的建议，我对StringJoiner做了一些实验（我不知道它的存在）

以下是一种方法：

List<String> deck = new ArrayList<>();
deck.add("Ace of Clubs");
deck.add("Two of Clubs");
deck.add("Three of Clubs");

StringJoiner stringJoiner = new StringJoiner("|", "{", "}");
for (String card : deck) {
  stringJoiner.add(card);
}
System.out.println(stringJoiner.toString());

这将作为输出提供：

{Ace of Clubs|Two of Clubs|Three of Clubs}

也就是说，我不确定为什么要使用toString方法进行洗牌，因为这样做没有意义？如果是为了打印，就按照马腾的建议复制一份