正则表达式替换括号()之间的内容

发布于 2024-11-01 10:57:08 字数 100 浏览 1 评论 0原文

我尝试了这段代码：

string.replaceAll("\\(.*?)","");

但它返回 null。我缺少什么？

原文

I tried this code:

string.replaceAll("\\(.*?)","");

But it returns null. What am I missing?

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梦里人 2024-11-08 10:57:08

尝试：

string.replaceAll("\\(.*?\\)","");

您没有转义第二个括号，也没有在第一个括号中添加额外的“\”。

Try:

string.replaceAll("\\(.*?\\)","");

You didn't escape the second parenthesis and you didn't add an additional "\" to the first one.

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緦唸λ蓇 2024-11-08 10:57:08

首先，您要删除括号及其内容吗？尽管问题的标题表明“否”，但我假设您也确实希望删除括号。

其次，括号之间的内容可以包含嵌套匹配的括号吗？该解决方案假设是。由于 Java 正则表达式风格不支持递归表达式，因此解决方案是首先制作一个与“最里面”括号集匹配的正则表达式，然后以迭代方式应用该正则表达式，从内到外替换它们。这是一个经过测试的 Java 程序，它正确删除（可能是嵌套的）括号及其内容：

import java.util.regex.*;
public class TEST {
    public static void main(String[] args) {
        String s = "stuff1 (foo1(bar1)foo2) stuff2 (bar2) stuff3";
        String re = "\\([^()]*\\)";
        Pattern p = Pattern.compile(re);
        Matcher m = p.matcher(s);
        while (m.find()) {
            s = m.replaceAll("");
            m = p.matcher(s);
        }
        System.out.println(s);
    }
}

测试输入：

"stuff1 (foo1(bar1)foo2) stuff2 (bar2) stuff3"

测试输出：

"stuff1  stuff2  stuff3"

请注意，lazy-dot-star 解决方案永远不会工作，因为在嵌套时它无法匹配最里面的一组括号。（即它错误地匹配：上面示例中的 (foo1(bar1)。）这是一个非常常见的正则表达式错误：永远不要在存在时使用点是一个更精确的表达式！在这种情况下，“最里面”的一组匹配括号之间的内容由任何不是左括号或右括号的字符组成，（即使用： [^()]* 而不是：.*?）。

First, Do you wish to remove the parentheses along with their content? Although the title of the question indicates no, I am assuming that you do wish to remove the parentheses as well.

Secondly, can the content between the parentheses contain nested matching parentheses? This solution assumes yes. Since the Java regex flavor does not support recursive expressions, the solution is to first craft a regex which matches the "innermost" set of parentheses, and then apply this regex in an iterative manner replacing them from the inside-out. Here is a tested Java program which correctly removes (possibly nested) parentheses and their contents:

import java.util.regex.*;
public class TEST {
    public static void main(String[] args) {
        String s = "stuff1 (foo1(bar1)foo2) stuff2 (bar2) stuff3";
        String re = "\\([^()]*\\)";
        Pattern p = Pattern.compile(re);
        Matcher m = p.matcher(s);
        while (m.find()) {
            s = m.replaceAll("");
            m = p.matcher(s);
        }
        System.out.println(s);
    }
}

Test Input:

"stuff1 (foo1(bar1)foo2) stuff2 (bar2) stuff3"

Test Output:

"stuff1  stuff2  stuff3"

Note that the lazy-dot-star solution will never work, because it fails to match the innermost set of parentheses when they are nested. (i.e. it erroneously matches: (foo1(bar1) in the example above.) And this is a very commonly made regex mistake: Never use the dot when there is a more precise expression! In this case, the contents between an "innermost" set of matching parentheses consists of any character that is not an opening or closing parentheses, (i.e. Use: [^()]* instead of: .*?).

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