Alphanumeric range checker - whether B3 is in B1:B10

Question

How to write an alphanumeric range checker in java which will check if the given alphanumeric value is within the range.

For example: input: B3, range: B1:B10 - true
B1, B1:B10 - true
B10, B1:B10 - true
B1, B3:B10 - false

My attempt is failing for more than 1 digit numbers, example in B3:B10, the second prefix should be 'B' and num should be 10 but I get B1 and 0. Is there anything wrong with the regex?

public class Main {

public static final String RANGE_PATTERN = "(.+)(\\d)+:(.+)(\\d)+";
public static final String INPUT_PATTERN = "(.+)(\\d)+";
public static final Pattern P1 = Pattern.compile(RANGE_PATTERN);
public static final Pattern P2 = Pattern.compile(INPUT_PATTERN);

public static void main(String[] args) {
    System.out.println(checkWithInRange("B3:B10", "B7"));
}

public static boolean checkWithInRange(String range, String input) {
    Matcher m1 = P1.matcher(range);
    Matcher m2 = P2.matcher(input);
    if (m1.find() && m2.find()) {
        String prefix1 = m1.group(1);
        String num1 = m1.group(2);
        String prefix2 = m1.group(3);
        String num2 = m1.group(4);

        String inputPrefix = m2.group(1);
        String inputNum = m2.group(2);

        if (prefix1.equalsIgnoreCase(prefix2) && prefix2.equalsIgnoreCase(inputPrefix)) {
            int n1 = Integer.parseInt(num1);
            int n2 = Integer.parseInt(num2);
            int n3 = Integer.parseInt(inputNum);
            if (n3 >= n1 && n3 <= n2) {
                return true;
            }
        }
    }
    return false;
}
}

Answer 1

Use "(.+?)... to receive the shortest sequence (without digit). Or better yet "(\\D+)....

Use (\\d+) instead of (\\d)+ so that m.group(i) is the entire string of digits.

No need to use a null check on the groups, maybe you intended an optional prefix: (\\D*).

Did you intend find() or should it match the entire string: matches()?

Answer 2

Thanks to Joop Eggen

I changed my regex as below,

public static final String RANGE_PATTERN = "(\\D+)(\\d+):(\\D+)(\\d+)";
public static final String INPUT_PATTERN = "(\\D+)(\\d+)";

Now it works with the above code.