正则表达式无法按预期工作-JAVA

Question

I am using the following regex "location in \\\\((.*?)\\\\)"

against the following string: pro 300\\nlocation in ("aaa","bbb")

according to online regex test for java, the result should be "aaa","bbb" but when I run that in java code like this:

conditions.replaceAll("location in \\((.*?)\\)", "$1");

I get pro 300"aaa","bbb"

What I am doing wrong? Thanks in advance.

Answer 1

replaceAll() is replacing the part of conditions matched by group(0) of your regex.

To retrieve only the part inside (...) you need to use:

Pattern p = Pattern.compile("location in \\((.*?)\\)");
Matcher m = p.matcher(conditions);
if (m.find())
{
    String s = m.group(1);
}

This will retrieve the inner bracket of your regular expression (.*?)

Answer 2

Additionally to Rossiar's answer, if you don't want to use Pattern and Matcher classes and just want to use replaceAll method then your code is working as expected , you have below string:

pro 300\nlocation in ("aaa","bbb")
         ^^^^^^^^^^^^^^^^^^^^^^^^^ and you replace this by "aaa","bbb"

So, your final string is:

pro 300\n"aaa","bbb"

String.replaceAll

If you want just to get "aaa","bbb" using replaceAll , you will have to match the complete string by using:

conditions = conditions.replaceAll(".*location in \\((.*?)\\).*", "$1");
                                    ^--------- Note ---------^

Or for your specific string you could use:

"pro 300\nlocation in (\"aaa\",\"bbb\")".replaceAll(".*\\((.*?)\\).*", "$1");

I can't test it right now if \\n is not being matched by .* , so in case it isn't then you can replace multilines by using single line flag or doing a regex trick:

Single line flag

"pro 300\nlocation in (\"aaa\",\"bbb\")".replaceAll("(?s).*\\((.*?)\\).*", "$1");

Working demo

Regex trick

"pro 300\nlocation in (\"aaa\",\"bbb\")".replaceAll("[\\s\\S]*\\((.*?)\\)[\\s\\S]*", "$1");

Working demo