有没有一种简单的方法可以将 java 字符串转换为包括变音符号在内的标题大小写，无需第三方库

Question

Is there a simple way to convert java string to title case including diacritics, without third party library.

I have found this old question but I think that Java has got many improvement since.
Is there a method for String conversion to Title Case?

Examples:

• JEAN-CLAUDE DUSSE
• sinéad o'connor
• émile zola
• O'mALLey

Expected results:

• Jean-Claude Dusse
• Sinéad O'Connor
• Émile Zola
• O'Malley

Answer 1

I use this method with regex:

public static void main(String[] args) {

    System.out.println(titleCase("JEAN-CLAUDE DUSSE"));
    System.out.println(titleCase("sinéad o'connor"));
    System.out.println(titleCase("émile zola"));
    System.out.println(titleCase("O'mALLey"));
}

public static String titleCase(String text) {

    if (text == null)
        return null;

    Pattern pattern = Pattern.compile("\\b([a-zÀ-ÖØ-öø-ÿ])([\\w]*)");
    Matcher matcher = pattern.matcher(text.toLowerCase());

    StringBuilder buffer = new StringBuilder();

    while (matcher.find())
        matcher.appendReplacement(buffer, matcher.group(1).toUpperCase() + matcher.group(2));

    return matcher.appendTail(buffer).toString();
}

I have tested with your strings.

Here is the results to output:

Jean-Claude Dusse
Sinéad O'Connor
Émile Zola
O'Malley

Answer 2

Two ways to achieve this -

Using Apache Commons Library

public static String convertToTileCase(String text) {
    return WordUtils.capitalizeFully(text);
}

Custom function

private final static String WORD_SEPARATOR = " ";

public static String changeToTitleCaseCustom(String text) {
    if (text == null || text.isEmpty()) {
        return text;
    }

    return Arrays.stream(text.split(WORD_SEPARATOR))
            .map(word -> word.isEmpty()
                    ? word
                    : Character.toTitleCase(word.charAt(0)) + word.substring(1).toLowerCase()
            )
            .collect(Collectors.joining(WORD_SEPARATOR));
}

Calling above custom function -

System.out.println(
            changeToTitleCaseCustom("JEAN-CLAUDE DUSSE") + "\n" +
                    changeToTitleCaseCustom("sinéad o'connor") + "\n" +
                    changeToTitleCaseCustom("émile zola") + "\n" +
                    changeToTitleCaseCustom("O'mALLey") + "\n");

Output -

Jean-claude Dusse
Sinéad O'connor
Émile Zola
O'malley