How to convert a Java string against a pattern regex?

Question

I want to convert a component version (for example 2.6.0) to this form G02R06C00. I think it's possible with regex and pattern with Java but I don't found how. I have seen examples to match a string against a pattern (in this case the regex would be G\d\dR\d\dC\d\d I guess), but I don't find how to convert a string to other string with a pattern. Thanks in advance.

What I have done is:

String gorocoVersion = version.replaceAll("(\\d*)\\.(\\d*)\\.(\\d*)", "G$1R$2C$3");

that produces G2R6C0, it's missing yet to add 0 to match 2 digits. So, I have to split input string before and I can't anymore use replaceAll, that's why I was looking for more clever option that automatically add 0 before simple digit too according to the output pattern G\d\dR\d\dC\d\d, like we can find in word or excel

Something that works with snapshot version but it's very ugly :

/**
 * @return version in G00R00C00(-SNAPSHOT) format.
 */
private String formatVersion() {
    String gorocoVersion = "";
    if (StringUtils.isNotBlank(version)) {
        String[] versionTab = version.split("\\.");
        String partG = String.format("%02d", Integer.parseInt(versionTab[0]));
        String partR = String.format("%02d", Integer.parseInt(versionTab[1]));

        String partC = versionTab[2];
        String snapshotSuffix = "-SNAPSHOT";
        if (partC.endsWith(snapshotSuffix)) {
            partC = String.format("%02d",
                    Integer.parseInt(partC.substring(0, partC.indexOf('-')))) + snapshotSuffix;
        } else {
            partC = String.format("%02d", Integer.parseInt(partC));
        }

        gorocoVersion = "G" + partG + "R" + partR + "C" + partC;
    }
    return gorocoVersion;
}

I want to know if it exists a function to convert a string to another string who matches a pattern. I have the input string "2.6.0", I have the output pattern "G\d\dR\d\dC\d\d" but is there a function to create an output string matching this pattern ? that is to say G02R06C00 — Nono
– Nono, Commented Apr 1, 2020 at 10:06
Ah, you are looking for string format. Or, match and capture your numbers and then replace (with String.replaceAll) using backreferences in the replacement to point to captured numbers. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Apr 1, 2020 at 10:07
yes I had seen replaceAll but I was looking something more clever, which could replace a string expression automatically towards an output pattern and also add automatically 0 before simple digit, thanks to the output pattern "G\d\dR\d\dC\d\d". According to your response, wHat I have done is : String gorocoVersion = version.replaceAll("(\\d*)\\.(\\d*)\\.(\\d*)", "G$1R$2C$3"); that produces G2R6C0, it's missing yet to add 0 to match 2 digits — Nono
– Nono, Commented Apr 1, 2020 at 13:03

Ilya Lysenko · Accepted Answer · 2020-04-01 20:25:16Z

0

Try this method:

private static String formatVersion(String version) {
    Pattern pattern = Pattern.compile("^(\\d+)\\.(\\d+)\\.(\\d+)(-SNAPSHOT)*$");
    Matcher matcher = pattern.matcher(version);
    if (matcher.find()) {
        return String.format("G%02dR%02dC%02d", Integer.parseInt(matcher.group(1)), Integer.parseInt(matcher.group(2)), Integer.parseInt(matcher.group(3)));
    } else {
        throw new IllegalArgumentException("Unsupported version format");
    }
}

Output for the version param value 2.6.0:

G02R06C00

edited Apr 1, 2020 at 20:25

answered Apr 1, 2020 at 15:20

Ilya Lysenko

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3 Comments

Nono Over a year ago

Great ! Thanks, I'm trying to adapt your code in order to work with -SNAPSHOT at the end too

Ilya Lysenko Over a year ago

I've updated the expression, now it will work and with the -SNAPSHOT suffix. If you want to add or to do something else with this suffix, use the matcher's group 4.

Nono Over a year ago

yes I had updated my code in other message as you can see. Thank you Ilya :)

Nono · Accepted Answer · 2020-04-01 17:11:11Z

Thanks a lot Ilya, here my final code which accepts SNAPSHOT and also x.y versions :

private String formatVersion(String version) {
    if (StringUtils.isNotBlank(version)) {
        Pattern pattern = Pattern.compile("^(\\d+)\\.(\\d+)\\.?(\\d+)?(-\\w*)?");
        Matcher matcher = pattern.matcher(version);
        if (matcher.find()) {
            return String.format("G%02dR%02dC%02d%s", Integer.parseInt(matcher.group(1)),
                    Integer.parseInt(matcher.group(2)),
                    matcher.group(3) != null ? Integer.parseInt(matcher.group(3)) : 0,
                    matcher.group(4) != null ? matcher.group(4) : "");
        }
    }
    return version;
}

With this code 2.6 gives G02R06C00 and 2.6.1-SNAPSHOT gives G02R06C01-SNAPSHOT, perfect :)

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