Java 正则表达式替换为捕获组 [英] Java Regex Replace with Capturing Group

问题描述

有没有办法用捕获组的修改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 乘以 3 替换所有出现的内容.

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

好像出了点问题:(

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();
}

它抛出一个 IllegalStateException: No match found

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 :(

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))));
}

要获得第一个匹配项，请使用 #find().之后，您可以使用 #group(1) 来引用第一个匹配项，并将所有匹配项替换为第一个 maches 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.

如果你想用匹配的值乘以 3 来替换每个匹配:

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());

您可能需要查看Matcher 的文档，其中详细介绍了这一点以及更多内容.

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

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