The regular expression used in JavaScript does not work in Java

Question

replace(/[.?+^$[\]\\(){}|-]/g, '\\$&');

But it doesn't work in Java. So I changed the code as follows.

replace(/[.?+^$[\\]\\\\(){}|-]/g, '\\\\$&');

It doesn't work when I change it. Please help me :(

In java, you need to use double quotes instead of quote slashes for regex: "[.?+^$[\\]\\\\(){}|-]". Also, if you want to replace all occurrences, you need to use String.replaceAll — Hao Wu
– Hao Wu, Commented Nov 20, 2020 at 2:00
Thank you for your answer. replaceAll(?"[?]+^$[\]\\\\(){}|-", "\\\\$&") results in a blank space. — lmy
– lmy, Commented Nov 20, 2020 at 3:35

The fourth bird · Accepted Answer · 2020-11-20 22:14:29Z

2

In Java, replace does not take a regex in the constructor, for that you need replaceFirst.

But as you are using the /g flag in Javascript for all replacements, you can use replaceAll.

In Javascript, this part $& in the replacement points to the full match.

So you want to replace the full match (which is one of these characters [.?+^$[\]\\(){}|-]) prepended by a \

In Java you can use $0 instead to refer to the full match.

You can also escape the opening square bracket in the character class \\[

For example

System.out.println("{test?test^}".replaceAll("[.?+^$\\[\\]\\\\()\\{}|-]", "\\\\$0"));

Output

\{test\?test\^\}

The same output in Javascript

console.log("{test?test^}".replace(/[.?+^$[\]\\(){}|-]/g, '\\$&'));

answered Nov 20, 2020 at 22:14

The fourth bird

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