I am trying to create a regex that will capture string between the square brackets, and if there is a number like (1234) then that should be excluded

I am using the regex

\[(.*?)\]

Suppose the sample data is

requests[45180], indices[movies]

In this case, I get the output as :

[45180]
[movies]

But my expected output is :

movies

Code:

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexMatcher {
    private static String REGEX = "\\[(.*?)\\]";
    private static String NUMBERS_REGEX = "\\d ";
    private static List sampleData = Arrays.asList("test from [a.b.v1.2.0.71-0] to [a.b.v1.2.0.73-0]",
            "requests[45180], indices[movies]");

    public static void main(String[] args) {
        Pattern pattern = Pattern.compile(REGEX);
        Pattern numberPattern = Pattern.compile(NUMBERS_REGEX);
        for (Object data : sampleData) {
            List<String> indices = new ArrayList<>();
            Matcher matcher = pattern.matcher(data.toString());

            while (matcher.find()) {
                String index = matcher.group().replaceAll("[\\[\\]'] ", "");
                Matcher numberMatcher = numberPattern.matcher(index);
                if (!numberMatcher.matches())
                    indices.add(index);
                
            }
            if (indices.size() > 0)
                System.out.println("Indices: "   indices);
        }
    }
}

Can anyone please help me resolve this issue?

CodePudding user response：

If your expected output is "movies", and you don't want to match digits in between the square brackets and not match empty strings, you can use a capture group:

\[([^\]\[\d] )]

• \[ Match [
• ( Capture group 1
  • [^\]\[\d] match 1 chars other than [ ] or a digit
• ) Close group 1
• ] Match ]

Regex demo | Java demo

In Java:

String regex = "\\[([^\\]\\[\\d]*)\\]";

Example

String regex = "\\[([^\\]\\[\\d] )]";
String string = "requests[45180], indices[movies]";

Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(string);

while (matcher.find()) {
    System.out.println(matcher.group(1));
}

Output

movies

CodePudding user response：

You can use either of

\[([^\]\[]*[^\d\[\]][^\]\[]*)]
\[(?!\d ])([^\]\[]*)]

See the regex demo #1 and regex demo #2.

In Java, you will need to double escape the backslashes in the string literals:

private static String REGEX = "\\[[^\\]\\[]*[^\\d\\[\\]][^\\]\\[]*]";
private static String REGEX = "\\[(?!\\d ])[^\\]\\[]*]";

Details:

• \[ - a [ char
• [^\]\[]* - zero or more chars other than [ and ]
• [^\d\[\]] - a char other than [, ] and a digit
• [^\]\[]* - zero or more chars other than [ and ]
• ] - a ] char.

And

• \[ - a [ char
• (?!\d ]) - immediately to the right, there cannot be one or more digits followed with a ] char
• [^\]\[]* - zero or more chars other than [ and ]
• ] - a ] char.

In your Java code, you probably can reduce the matching part with

while (matcher.find()) {
    String index = matcher.group(1);
    indices.add(index);
}

See the Java demo.