转义Java RegExp元字符 [英] Escape Java RegExp Metacharacters

问题描述

我正在尝试转义Java中的RegExp元字符.以下是我想要的:

I'm trying to escape a RegExp metacharacter in Java. Below is what I want:

INPUT STRING: "This is $ test"
OUTPUT STRING: "This is \$ test"

这是我当前正在执行的操作，但不起作用:

This is what I'm currently doing but it's not working:

String inputStr= "This is $ test";
inputStr = inputStr.replaceAll("$","\\$");

但是我得到了错误的输出:

But I'm getting wrong output:

"This is $ test$"

推荐答案

您需要:

inputStr.replaceAll("\\$", "\\\\\\$");

要替换的字符串需要2个反斜杠，因为 $ 在正则表达式中具有特殊含义.因此，必须对$进行转义，以获得: \ $ ，并且必须在Java字符串中对反斜杠 self 进行转义:"\\ $"

The String to be replaced needs 2 backslashes because $ has a special meaning in the regexp. So $ must be escaped, to get: \$, and that backslash must itself be escaped within the java String: "\\$".

替换字符串需要6个反斜杠，因为 \ 和 $ 在替换字符串中都有特殊含义:

The replacement string needs 6 backslashes because both \ and $ have special meaning in the replacement strings:

• \可用于转义替换字符串中的字符.
• $可用于在替换字符串中进行反向引用.

因此，如果您希望的替换字符串是"\ $"，则需要对这两个字符进行转义以获取: \\\ $ ，然后需要使用每个反斜杠-3个它们，即1个文字和2个用于转义的字符-必须也必须在Java字符串中进行转义:"\\\\\\ $" .

So if your intended replacement string is "\$", you need to escape each of those two characters to get: \\\$, and then each backslash you need to use - 3 of them, 1 literal and 2 for escapes - must also be escaped within the java String: "\\\\\\$".

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