How Can Java Regular Expressions Extract Numerical Values from Strings?

Utilizing Regular Expressions to Extract Values in Java

Seeking to extract numerical values from strings in the format "[some text] [some number] [some more text]", this article leverages Java's regular expression classes to accomplish the task.

The desired regular expression can vary, but the Java calls remain consistent. To use a regular expression string on source data, follow these steps:

1. Compile the regular expression into a Pattern object using Pattern.compile(regexString).
2. Create a Matcher object by calling matcher(sourceString) on the Pattern object.
3. Use find() on the Matcher object to determine if a pattern occurrence has been found in the source string.
4. If a match is found, use group() methods on the Matcher object to extract the desired values. The syntax is m.group(n), where n represents the group number within the regular expression.

Here's an example that extracts the first numerical value using the regular expression "^D (d ).*":

private static final Pattern p = Pattern.compile("^\D+(\d+).*");

public static void main(String[] args) {
    Matcher m = p.matcher("Testing123Testing");
    if (m.find()) {
        System.out.println("Extracted number: " + m.group(1));
    }
}

This code will print "123" as the extracted number.

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