使用包含括号'（''的正则表达式从字符串中提取子字符串

Question

I am trying to figure out how to extract a substring from a string but the string contains a bracket, and Java then complains that it is not enclosed and if I try and escape it then complains that its not a valid escaped character.

I have the following string:

[Monitor Status](/monitors#2972550?)] · [[Edit Monitor](/monitors#2972550/edit)] · [[Related Logs](/logs?query=)]
%%%

I'm am trying to extract the number after /monitors#. The number is in two places and will always be the same in both places so I'm just trying to extract the first number.

Below is what I currently have:

Pattern pattern = Pattern.compile("[Monitor Status]/monitors#(\\d+)");                   
Matcher matcher = pattern.matcher(monitorDetails);
if (matcher.find())
{
     String monitor_id = matcher.group(1);
     monitorDetailsContainer.setVisibility(View.VISIBLE);
}

With the above, I don't have the ( between ] and /monitors but when I do Android Studio then says unclosed group . If I try and escape the slash \\( it then says illegal escape character.

What I am expecting to get back is 2972550 .

Answer 1

You missed some chars on the way to the digits and failed to escape the ( , ) and [ , use

Pattern pattern = Pattern.compile("\\[Monitor Status]\\(/monitors#(\\d+)");                   
Matcher matcher = pattern.matcher(monitorDetails);
if (matcher.find())
{
     String monitor_id = matcher.group(1);
     monitorDetailsContainer.setVisibility(View.VISIBLE);
}

Here is a regex demo and an online Java demo .

Details

• \\[ - a [
• Monitor Status - a literal substring
• ] - a literal ]
• \\( - a literal (
• / - a /
• monitors# - a literal substring
• (\\d+) - Group 1: one or more digits.