String.replaceAll方法详析(正则妙用)

String str1 = "createTime";
String str2 = "createTimeAt";
String regex = "([A-Z])+";

System.out.println(str1.replaceAll(regex, "_$1").toLowerCase());
System.out.println(str2.replaceAll(regex, "_$1").toLowerCase());

//result
//create_time
//create_time_at

"createTime".replaceAll("([A-Z]+)","_$1")

public String replaceAll(String regex, String replacement) {
    return Pattern.compile(regex).matcher(this).replaceAll(replacement);
}

public String replaceAll(String replacement) {
    reset();
    boolean result = find();
    if (result) {
      StringBuilder sb = new StringBuilder();
      do {
        appendReplacement(sb, replacement);
        result = find();
      } while (result);
      appendTail(sb);
      return sb.toString();
    }
    return text.toString();
  }

String data = "哈哈哈，xjjdog的手机号码是:12345678901，你会打给我吗";
//通过Matcher的分组功能，可以提取出上面字符串中的手机号
Matcher matcher = Pattern.compile(".*(xjjdog的手机号码是:([0-9]{11}))").matcher(data);
while (matcher.find()) {
  System.out.println("G0:" + matcher.group(0));
  System.out.println("G1:" + matcher.group(1));
  System.out.println("G2:" + matcher.group(2));
}
//result
//G0:哈哈哈，xjjdog的手机号码是:12345678901
//G1:xjjdog的手机号码是:12345678901
//G2:12345678901

public static String camelToUnderline(String camelName) {
return camelName.replaceAll("([A-Z]+)", "_$1").toLowerCase();
}

public static String underlineToCamel(String underlineName) {
    Matcher matcher = Pattern.compile("(_[a-z]{1})").matcher(underlineName);
    StringBuffer result = new StringBuffer();
    while (matcher.find()) {
      String replacement = matcher.group(1);
      matcher.appendReplacement(result, replacement.replace("_", "").toUpperCase());
    }
    matcher.appendTail(result);
    return result.toString();
}

 public static String getCamelCaseString(String inputString) {
    StringBuilder sb = new StringBuilder();
    boolean nextUpperCase = false;
    for (int i = 0; i < inputString.length(); i++) {
      char c = inputString.charAt(i);
      switch (c) {
        case '_':
        case '-':
        case '@':
        case '$':
        case '#':
        case ' ':
        case '/':
        case '&':
          if (sb.length() > 0) {
            nextUpperCase = true;
          }
          break;
        default:
          if (nextUpperCase) {
            sb.append(Character.toUpperCase(c));
            nextUpperCase = false;
          } else {
            sb.append(Character.toLowerCase(c));
          }
          break;
      }
    }
    return sb.toString();
  }