依次打印 ArrayList 中的所有字符

Question

我有这个 ArrayList

ArrayList<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());