Java 正则表达式 不区分大小写，带有德语变音符号

Question

这个问题已经有答案了:

Java case-insensitive regex matching doesn't work with letter Ñ (1 个回答)

已关闭 3 年前。

我想定位/替换文本中的单词。单词示例是“TÜTÜ”。这是代码:

    final String regexX = "TÜTÜ";
    final String string = "dsad dasdasd dasd \n"
            + "dsds\n"
            + " dd \n"
            + "sadsd.sdasd. \n"
            + " universität \n"
            + " blö \n"
            + " Blö\n"
            + " ble\n"
            + "üeee \n"
            + " Wörterbuch \n"
            + "Das gute alte Tütü wird";
    final String subst = "";

    final Pattern pattern = Pattern.compile(regexX, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE);
    final Matcher matcherX = pattern.matcher(string);

    final String result = matcherX.replaceAll(subst);

    System.out.println("Substitution result: " + result);

结果是，没有任何内容被替换。这实际上是从 regex101.com 复制的代码，其中德语 TÜTÜ 也无法识别。不区分大小写对德语“Umlaute”不起作用是真的吗？还是有办法让它起作用？

Answer 1

final Pattern pattern = Pattern.compile(regexX, Pattern.MULTILINE | Pattern.CASE_INSENSITIVE);

您需要添加Pattern.UNICODE_CASE ，否则仅 US-ASCII 字符集用于 CASE_INSENSITIVE:

Enables Unicode-aware case folding. When this flag is specified then case-insensitive matching, when enabled by the CASE_INSENSITIVE flag, is done in a manner consistent with the Unicode Standard. By default, case-insensitive matching assumes that only characters in the US-ASCII charset are being matched.

Unicode-aware case folding can also be enabled via the embedded flag expression (?u).

Specifying this flag may impose a performance penalty.