依次打印 ArrayList 中的所有字符

Question

我有这个 ArrayListArrayList<Character> wrongLetters;还有这个系统System.out.println("Number of errors: " + wrongLetters.size() + " (" +  String.join("", String.valueOf(wrongLetters)) + ")");它现在像这样打印Number of errors: 9 ([X, M, S, K, B, Q, L, I, U])但我怎样才能做到这样Number of errors: 9 (XMSKBQLIU)

Answer 1

Java 8 或更高版本：

final String result = wrongLetters.stream().map(String::valueOf).collect(Collectors.joining());

System.out.println("Number of errors: " + wrongLetters.size() + " (" +  result + ")");

Answer 2

从字符的数组列表中创建一个字符串

String str = "";

for (Character c : wrongLetters) {

    str += c;

} 

然后 ：

System.out.println("Number of errors: " + wrongLetters.size() + " (" +  String.join("", str) + ")");

或制作一个字符串生成器：

StringBuilder stringBuilder= new StringBuilder(wrongLetters.size());

    for (Character c : wrongLetters) {

      stringBuilder.append(c);

    }

然后：

       System.out.println("Number of errors: " + wrongLetters.size() + " (" +  String.join("", stringBuilder.toString()) + ")");

Answer 3

愚蠢的答案（只需删除非字母数字）：

System.out.println("Number of errors: " + wrongLetters.size() + " (" + String.join("", String.valueOf(wrongLetters).replaceAll("[^A-Za-z0-9]", ""))+ ")");

Java 8+ 的另一个：

StringJoiner joiner = new StringJoiner("");

    wrongLetters.stream().forEach(err -> joiner.add(String.valueOf(err)));

    System.out.println("Number of errors: " + wrongLetters.size() + " (" + joiner + ")");

没有 Java 8（使用 StringBuilder）：

StringBuilder sb = new StringBuilder(" (");

    for (Character character : wrongLetters) {

        sb.append(character);

    }

    sb.append(")");

    System.out.println("Number of errors: " + wrongLetters.size() + sb.toString());