Java Regex替换为捕获组 [英] Java Regex Replace with Capturing Group

问题描述

有没有办法用修改后的捕获组内容替换正则表达式？

Is there any way to replace a regexp with modified content of capture group?

示例：

Pattern regex = Pattern.compile("(\\d{1,2})");
Matcher regexMatcher = regex.matcher(text);
resultString = regexMatcher.replaceAll("$1"); // *3 ??

我想用$ 1替换所有出现次数乘以3。

And I'd like to replace all occurrence with $1 multiplied by 3.

编辑

看起来有些不对劲：（

如果我使用

Pattern regex = Pattern.compile("(\\d{1,2})");
Matcher regexMatcher = regex.matcher("12 54 1 65");
try {
    String resultString = regexMatcher.replaceAll(regexMatcher.group(1));
} catch (Exception e) {
    e.printStackTrace();
}

抛出IllegalStateException：找不到匹配项

It throws an IllegalStateException: No match found

但是

Pattern regex = Pattern.compile("(\\d{1,2})");
Matcher regexMatcher = regex.matcher("12 54 1 65");
try {
    String resultString = regexMatcher.replaceAll("$1");
} catch (Exception e) {
    e.printStackTrace();
}

工作正常，但我无法更改$ 1 :(

works fine, but I can't change the $1 :(

编辑

现在，它正在工作：）

推荐答案

怎么样：

if (regexMatcher.find()) {
    resultString = regexMatcher.replaceAll(
            String.valueOf(3 * Integer.parseInt(regexMatcher.group(1))));
}

要获得第一场比赛，请使用 #find（ ）。之后，您可以使用 #group（1）来引用第一个匹配，并将第一个匹配值替换所有匹配值乘以3.

To get the first match, use #find(). After that, you can use #group(1) to refer to this first match, and replace all matches by the first maches value multiplied by 3.

如果您想用该匹配值替换每个匹配的值乘以3：

And in case you want to replace each match with that match's value multiplied by 3:

    Pattern p = Pattern.compile("(\\d{1,2})");
    Matcher m = p.matcher("12 54 1 65");
    StringBuffer s = new StringBuffer();
    while (m.find())
        m.appendReplacement(s, String.valueOf(3 * Integer.parseInt(m.group(1))));
    System.out.println(s.toString());

您可能想查看 Matcher 的文档，其中和详细介绍了更多的东西。

You may want to look through Matcher's documentation, where this and a lot more stuff is covered in detail.

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