Comparing version number strings (major, minor, revision, beta)

Question

I have an application that communicates with the firmware of a device. As there are changes to the firmware, it is versioned with the format {major}.{minor}.{revision}

Answer 1

For my project I have used this approach by following Semantic Versioning 2.0.0:

private static String[] formatVersionString(String[] strArr){
    //remove trailing 0s
    List list = new ArrayList<>();
    boolean foundChar = false;
    for(int i=strArr.length-1;i>=0;i--){
        String curChar = strArr[i];
        if(curChar.equals("0") && !foundChar){
            continue;
        } else{
            list.add(strArr[i]);
            foundChar = true;
        }

    }
    Collections.reverse(list);
    return list.toArray(new String[list.size()]);
}

private static String getPreReleaseBuildStr(String buildStr){
    //removing build metadata
    if(buildStr == null){
        return null;
    }
    String [] a = buildStr.split("\\+");
    if(a.length>0){
        return a[0];
    } else{
        return null;
    }
}

private static int compareVersionString(String str1,String str2){
    int ret = 0;
    String[] verStr1 = formatVersionString(str1.split("\\."));
    String[] verStr2 = formatVersionString(str2.split("\\."));

    int i = 0;
    // set index to first non-equal ordinal or length of shortest version string
    while (i < verStr1.length && i < verStr2.length && verStr1[i].equals(verStr2[i])) {
        i++;
    }

    // compare first non-equal ordinal number
    if (i < verStr1.length && i < verStr2.length) {
        int diff = 0;
        try{
            if(verStr1[i] == null || verStr1[i].trim().length() == 0) {
                verStr1[i] = "0";
            }
            if(verStr2[i] == null || verStr2[i].trim().length() == 0) {
                verStr2[i] = "0";
            }
            diff = Integer.valueOf(verStr1[i]).compareTo(Integer.valueOf(verStr2[i]));
        }catch(NumberFormatException e){
            diff = verStr1[i].compareTo(verStr2[i]);
        } finally{
            ret = Integer.signum(diff);
        }
    } else{
        // the strings are equal or one string is a substring of the other
        // e.g. "1.2.3" = "1.2.3" or "1.2.3" < "1.2.3.4"

        ret = Integer.signum(verStr1.length - verStr2.length);
    }

    return ret;
}

/**
 * Compares two version strings.
 * follow this link for more info http://semver.org/
 *
 * Use this instead of String.compareTo() for a non-lexicographical
 * comparison that works for version strings. e.g. "1.10".compareTo("1.6").
 *
 * Ex:--
 * //1.0.0-alpha < 1.0.0-alpha.1 < 1.0.0-alpha.beta < 1.0.0-beta < 1.0.0-beta.2 < 1.0.0-beta.11 < 1.0.0-rc.1 < 1.0.0 < 2.0.0.6
 *
 * @param str1 a string of ordinal numbers separated by decimal points.
 * @param str2 a string of ordinal numbers separated by decimal points.
 * @return The result is a negative integer if str1 is _numerically_ less than str2.
 *         The result is a positive integer if str1 is _numerically_ greater than str2.
 *         The result is zero if the strings are _numerically_ equal.
 */

public static int versionCompare(String str1, String str2) {

    int ret = 0;
    String[] val1 = str1.split("-");
    String[] val2 = str2.split("-");

    String preReleaseVer1 = null, preReleaseVer2 = null;
    if(val1.length>1){
        preReleaseVer1 = getPreReleaseBuildStr(val1[1]);
    }
    if(val2.length>1){
        preReleaseVer2 = getPreReleaseBuildStr(val2[1]);
    }

    ret = compareVersionString(val1[0],val2[0]);

    if(ret == 0){
        //if both version are equal then compare with pre_release String
        if(preReleaseVer1 == null && preReleaseVer2 == null){
              ret = 0;
        } else if(preReleaseVer1 == null && preReleaseVer2!=null){
            //1.0.0 > 1.0.0-beta
              ret = 1;
        } else if(preReleaseVer1 != null && preReleaseVer2==null){
            //1.0.0-beta < 1.0.0
            ret = -1;
        } else{
            //both hasve pre release string
            ret = compareVersionString(preReleaseVer1,preReleaseVer2);
        }
    }

    return ret;
}

Use versionCompare(String str1, String str2) method for any comparison

Code Example:---

public class Main
{
    public static void main (String[] args)
    {
        //1.0.0-alpha < 1.0.0-alpha.1 < 1.0.0-alpha.beta < 1.0.0-beta < 1.0.0-beta.2 < 1.0.0-beta.11 < 1.0.0-rc.1 < 1.0.0

        Test(new String[]{"1.0.0-alpha","1.0.0-alpha.1","1.0.0-alpha.beta","1.0.0-beta",
        "1.0.0-beta.2","1.0.0-beta.11","1.0.0-rc.1","1.0.0","2.0.0.1"});  
    }
    private static void Test(String[] versions) {
        for (int i = 0; i < versions.length; i++) {
            for (int j = 0; j < versions.length; j++) {
            Test(versions[i], versions[j]);
            }
        }
    }

    private static void Test(String v1, String v2) {
        int result = versionCompare(v1,v2);
        String op = "==";
        if (result < 0) op = "<";
        if (result > 0) op = ">";
        System.out.printf("%s %s %s\n", v1, op, v2);
    }
}

The Output of the above example is given below:---

1.0.0-alpha == 1.0.0-alpha
1.0.0-alpha < 1.0.0-alpha.1
1.0.0-alpha < 1.0.0-alpha.beta
1.0.0-alpha < 1.0.0-beta
1.0.0-alpha < 1.0.0-beta.2
1.0.0-alpha < 1.0.0-beta.11
1.0.0-alpha < 1.0.0-rc.1
1.0.0-alpha < 1.0.0
1.0.0-alpha < 2.0.0.1
1.0.0-alpha.1 > 1.0.0-alpha
1.0.0-alpha.1 == 1.0.0-alpha.1
1.0.0-alpha.1 < 1.0.0-alpha.beta
1.0.0-alpha.1 < 1.0.0-beta
1.0.0-alpha.1 < 1.0.0-beta.2
1.0.0-alpha.1 < 1.0.0-beta.11
1.0.0-alpha.1 < 1.0.0-rc.1
1.0.0-alpha.1 < 1.0.0
1.0.0-alpha.1 < 2.0.0.1
1.0.0-alpha.beta > 1.0.0-alpha
1.0.0-alpha.beta > 1.0.0-alpha.1
1.0.0-alpha.beta == 1.0.0-alpha.beta
1.0.0-alpha.beta < 1.0.0-beta
1.0.0-alpha.beta < 1.0.0-beta.2
1.0.0-alpha.beta < 1.0.0-beta.11
1.0.0-alpha.beta < 1.0.0-rc.1
1.0.0-alpha.beta < 1.0.0
1.0.0-alpha.beta < 2.0.0.1
1.0.0-beta > 1.0.0-alpha
1.0.0-beta > 1.0.0-alpha.1
1.0.0-beta > 1.0.0-alpha.beta
1.0.0-beta == 1.0.0-beta
1.0.0-beta < 1.0.0-beta.2
1.0.0-beta < 1.0.0-beta.11
1.0.0-beta < 1.0.0-rc.1
1.0.0-beta < 1.0.0
1.0.0-beta < 2.0.0.1
1.0.0-beta.2 > 1.0.0-alpha
1.0.0-beta.2 > 1.0.0-alpha.1
1.0.0-beta.2 > 1.0.0-alpha.beta
1.0.0-beta.2 > 1.0.0-beta
1.0.0-beta.2 == 1.0.0-beta.2
1.0.0-beta.2 < 1.0.0-beta.11
1.0.0-beta.2 < 1.0.0-rc.1
1.0.0-beta.2 < 1.0.0
1.0.0-beta.2 < 2.0.0.1
1.0.0-beta.11 > 1.0.0-alpha
1.0.0-beta.11 > 1.0.0-alpha.1
1.0.0-beta.11 > 1.0.0-alpha.beta
1.0.0-beta.11 > 1.0.0-beta
1.0.0-beta.11 > 1.0.0-beta.2
1.0.0-beta.11 == 1.0.0-beta.11
1.0.0-beta.11 < 1.0.0-rc.1
1.0.0-beta.11 < 1.0.0
1.0.0-beta.11 < 2.0.0.1
1.0.0-rc.1 > 1.0.0-alpha
1.0.0-rc.1 > 1.0.0-alpha.1
1.0.0-rc.1 > 1.0.0-alpha.beta
1.0.0-rc.1 > 1.0.0-beta
1.0.0-rc.1 > 1.0.0-beta.2
1.0.0-rc.1 > 1.0.0-beta.11
1.0.0-rc.1 == 1.0.0-rc.1
1.0.0-rc.1 < 1.0.0
1.0.0-rc.1 < 2.0.0.1
1.0.0 > 1.0.0-alpha
1.0.0 > 1.0.0-alpha.1
1.0.0 > 1.0.0-alpha.beta
1.0.0 > 1.0.0-beta
1.0.0 > 1.0.0-beta.2
1.0.0 > 1.0.0-beta.11
1.0.0 > 1.0.0-rc.1
1.0.0 == 1.0.0
1.0.0 < 2.0.0.1
2.0.0.1 > 1.0.0-alpha
2.0.0.1 > 1.0.0-alpha.1
2.0.0.1 > 1.0.0-alpha.beta
2.0.0.1 > 1.0.0-beta
2.0.0.1 > 1.0.0-beta.2
2.0.0.1 > 1.0.0-beta.11
2.0.0.1 > 1.0.0-rc.1
2.0.0.1 > 1.0.0
2.0.0.1 == 2.0.0.1
3.5.6-beta == 3.5.6-beta
3.5.6-beta == 3.5.6-beta.0
3.5.6-beta.0 == 3.5.6-beta
3.5.6-beta.0 == 3.5.6-beta.0