How Can Java Regular Expressions Extract Numbers from Bracketed Text?

Using Java Code to Extract Values Using Regular Expressions

Java provides robust regex classes to manipulate strings and extract specific information. Imagine you have strings containing a number enclosed in brackets, like this:

[some text] [some number] [some more text]

To extract the number within these brackets, we can employ Java's regex classes. The following code snippet showcases how to perform this task:

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegexExtractor {

    public static void main(String[] args) {
        // Define the regular expression pattern
        Pattern pattern = Pattern.compile(".*\[(.*?)\].*");

        // Sample string to extract the value from
        String source = "[Text before number] [123] [Text after number]";

        // Create a matcher for the pattern using the source string
        Matcher matcher = pattern.matcher(source);

        // Find the first occurrence and extract the value within the brackets
        if (matcher.find()) {
            String extractedValue = matcher.group(1);
            System.out.println("Extracted value: " + extractedValue);
        }
    }
}

In this example, the pattern represents the regular expression that looks for any characters followed by a set of square brackets with one or more characters inside, which represents the value you want to extract.

The matcher is then created and applied to the source string. If a match is found, the group() method is used to retrieve the matching part of the string, which in this case is the value enclosed in brackets.

You can customize the regular expression according to your specific needs. For example, if you're looking for a specific format of number, you can specify the exact pattern.

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