java - 如何解决 Java 正则表达式中缺少的预处理操作？

Question

Java 不支持正则表达式中的预处理操作。如何解决 Java 中缺少的这个特性？

我想在 Java 中实现一个方法，它与这个GNU sed命令相同：

$ sed 's/\(^\|_\)\([a-z]\)/\U\2/g' <<< first_name
FirstName

sed 调用产生骆驼情况。

Answer 1

为什么不简单地使用老式的字符串操作？

String myStr = "first_name";
myStr = myStr.replace("_", " ");
myStr = StrUtils.Capitalize(myStr);
myStr = mystr.replace(" ", "");

StrUtils 来自http://commons.apache.org/lang/

如果您不想添加 StrUtils，拆分单词并替换第一个字符，只需将小写和大写字母之间的 ASCII 差异（我认为是 32）添加到 char。（或大写函数等...）

Answer 2

如果你试试

public static void main(String[] args) {
    System.out.println(toTitleCase("first_name"));
    System.out.println(toTitleCase("UPPER_CASE"));
    System.out.println(toTitleCase("ßßß_ßßß_dždždž"));
}

public static String toTitleCase(String s) {
    StringBuilder sb = new StringBuilder();
    for (String word : s.split("_+")) {
        sb.append(word.substring(0,1).toUpperCase());
        sb.append(word.substring(1).toLowerCase());
    }
    return sb.toString();
}

印刷

FirstName
UpperCase
SSßßSSßßDŽdždž

Answer 3

我现在用这个：

class camelcase
{
  public static void capitalize (String str, StringBuilder builder)
  {
    int length = str.length();
    if (length > 0) {
      builder.append (Character.toTitleCase(str.charAt(0)));
      if (length > 1)
        builder.append (str.substring(1).toLowerCase());
    }
  }

  public static String capitalize (String str)
  {
    StringBuilder builder = new StringBuilder();
    capitalize (str, builder);
    return builder.toString();
  }

  public static void camelcase (String str, StringBuilder builder)
  {
    for (String word : str.split("[ \\p{Punct}]+"))
      capitalize (word, builder);
  }

  public static String camelcase (String str)
  {
    StringBuilder builder = new StringBuilder();
    camelcase (str, builder);
    return builder.toString();
  }

  public static void main (String[] args)
  {
    String[] strings = new String[] {
      "", "a", "aa", "aa_bb", "aa bb", "aa - bb", "ß", "ßß", "ßß_ßß", "dždž"
    };
    for (String str : strings)
      System.out.println ("'" + str + "' -> '" + camelcase (str) + "'");
  }
}