Re: how to compare two version strings in java

From:

Daniele Futtorovic <da.futt.news@laposte.invalid>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 29 Jul 2008 03:05:58 +0200

Message-ID:

<g6lqe1$6fg$1@registered.motzarella.org>

On 28/07/2008 18:22, anywherenotes@gmail.com allegedly wrote:

Hi,

How would I compare two version strings, for example:
10.1.2.0 is greater than 10.0.0.0
and
10.1.2.0 is also greater than 9.0.0.0
however if I would compare those as String objects, obviously 9.0.0.0
would be greater than 10....

Is there a good way of doing it?
It's possible to split the string into numbers and do numeric
conversion, but if there's already a standard java class/method
handling this I'd like to use it.

Thank you.

For the fun of it:

<code>
package scratch;

import java.util.*;

public class Scratch
{
     private static class VersionStringComparator
             implements Comparator<String>
     {
         public int compare(String s1, String s2){
             if( s1 == null && s2 == null )
                 return 0;
             else if( s1 == null )
                 return -1;
             else if( s2 == null )
                 return 1;

             String[]
                 arr1 = s1.split("[^a-zA-Z0-9]+"),
                 arr2 = s2.split("[^a-zA-Z0-9]+")
             ;

             int i1, i2, i3;

             for(int ii = 0, max = Math.min(arr1.length, arr2.length);
ii <= max; ii++){
                 if( ii == arr1.length )
                     return ii == arr2.length ? 0 : -1;
                 else if( ii == arr2.length )
                     return 1;

                 try{
                     i1 = Integer.parseInt(arr1[ii]);
                 }
                 catch (Exception x){
                     i1 = Integer.MAX_VALUE;
                 }

                 try{
                     i2 = Integer.parseInt(arr2[ii]);
                 }
                 catch (Exception x){
                     i2 = Integer.MAX_VALUE;
                 }

                 if( i1 != i2 ){
                     return i1 - i2;
                 }

                 i3 = arr1[ii].compareTo(arr2[ii]);

                 if( i3 != 0 )
                     return i3;
             }

             return 0;
         }
     }

     public static void main(String[] ss){

         String[] data = new String[]{
             "2.0",
             "1.5.1",
             "10.1.2.0",
             "9.0.0.0",
             "2.0.0.16",
             "1.6.0_07",
             "1.6.0_07-b06",
             "1.6.0_6",
             "1.6.0_07-b07",
             "1.6.0_08-a06",
             "5.10",
             "Generic_127127-11",
             "Generic_127127-13"
         };

         List<String> list = Arrays.asList(data);
         Collections.sort(list, new VersionStringComparator());

         for(String s: list)
             System.out.println(s);
     }
}
</code>

<output>
   1.5.1
   1.6.0_6
   1.6.0_07
   1.6.0_07-b06
   1.6.0_07-b07
   1.6.0_08-a06
   2.0
   2.0.0.16
   5.10
   9.0.0.0
   10.1.2.0
   Generic_127127-11
   Generic_127127-13
</output>

--
DF.