我如何为一个甲板类写一个函数到String方法[duplicate]

Question

基本上，我有这个toString方法，它显示已排序的卡片。本质上，如果我有一副完整的牌，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，我已经通过一个简单的循环来完成这一操作，在开始处放置一个花括号，并循环显示deck中有多少个元素，添加deck.get(I).getCard()+“”的输出。最后从结尾减去三个字符，再加上一个花括号。但这不是一个很好的解决方案，是一个非常程序化的解决方案，我喜欢优雅的解决方案，我认为有一些函数可以为这种目的服务，但我不知道lambda表达式或其他任何一个，所以我想知道是否有人可以教我如何做到这一点。在下面你会找到我目前的解决方案。任何帮助都是感激的干杯！

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

根据MadProgammer的建议，我尝试了一些StringJoiner（我不知道它的存在）。

下面是一种方法：

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());

这给出了输出：

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

话虽如此，但我不知道为什么要在toString方法中进行洗牌，因为这样做没有意义？如果它是打印的，就像Maarten建议的那样创建一个副本。