Java Regex替换为捕获组

可能重复：
Java Regex替换为捕获组

有没有办法用修改后的捕获组内容替换正则表达式？

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。

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(); } 

它抛出IllegalStateException：找不到匹配项

但

 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，但我不能改变$ 1 🙁

EDIT2：

现在，它的工作:)

Answer 1

几年前Elliott Hughes在他的博客上发布了这个问题的最终解决方案。 Elliott不断向在线版本中的其他类引入无意义的依赖关系，所以我将在这里发布一个独立版本（依赖关系仅在main()方法的测试中）。

 import java.util.regex.*; /** * A Rewriter does a global substitution in the strings passed to its * 'rewrite' method. It uses the pattern supplied to its constructor, and is * like 'String.replaceAll' except for the fact that its replacement strings * are generated by invoking a method you write, rather than from another * string. This class is supposed to be equivalent to Ruby's 'gsub' when * given a block. This is the nicest syntax I've managed to come up with in * Java so far. It's not too bad, and might actually be preferable if you * want to do the same rewriting to a number of strings in the same method * or class. See the example 'main' for a sample of how to use this class. * * @author Elliott Hughes */ public abstract class Rewriter { private Pattern pattern; private Matcher matcher; /** * Constructs a rewriter using the given regular expression; the syntax is * the same as for 'Pattern.compile'. */ public Rewriter(String regex) { this.pattern = Pattern.compile(regex); } /** * Returns the input subsequence captured by the given group during the * previous match operation. */ public String group(int i) { return matcher.group(i); } /** * Overridden to compute a replacement for each match. Use the method * 'group' to access the captured groups. */ public abstract String replacement(); /** * Returns the result of rewriting 'original' by invoking the method * 'replacement' for each match of the regular expression supplied to the * constructor. */ public String rewrite(CharSequence original) { this.matcher = pattern.matcher(original); StringBuffer result = new StringBuffer(original.length()); while (matcher.find()) { matcher.appendReplacement(result, ""); result.append(replacement()); } matcher.appendTail(result); return result.toString(); } public static void main(String... args) throws Exception { String str = "12 54 1 65"; // anonymous subclass Rewriter tripler = new Rewriter("(\\d{1,2})") { public String replacement() { int intValue = Integer.valueOf(group(1)); return String.valueOf(intValue * 3); } }; System.out.println(tripler.rewrite(str)); // inline subclass System.out.println(new Rewriter("(\\d{1,2})") { public String replacement() { int intValue = Integer.valueOf(group(1)); return String.valueOf(intValue * 3); } }.rewrite(str)); } } 

Answer 2

不，你不能用正则表达式做到这一点。 正则表达式没有数值的概念，因此无法使用数字进行算术运算（假设您想将“12 54 1 65”转换为“36 162 3 195”）。

请注意，对于某些语言和正则表达式实现，您可以执行此操作（Perl作为Chris发布），但这不是正则表达式，尤其不是Java-regex。 你说你已经解决了这个问题，所以我想你采用了“手动”方式，将每个匹配转换为一个整数并将其乘以3。