Re: how to compare two version strings in java

anywherenotes@gmail.com wrote:


Yeah, I think you have to do the comparison yourself. I don't think
there's a standard class to do it for you.

package versionstring;

public class VersionString implements Comparable<VersionString> {

     final private String version;

     public VersionString(String version) {
         if( version.length() == 0 )
             throw new IllegalArgumentException(
                     "\"version\" may not be zero length" );
         String temp[] = version.split("\\.");
         for( String s : temp )
         {
             if( s == null )
               throw new IllegalArgumentException(
                 "\"version\" contains a null version sub-string");
             if( s.length() == 0 )
               throw new IllegalArgumentException(
                "\"version\" contains a zero lenght version sub-string" );
             Integer.parseInt(s);
         }
         this.version = version;
     }

     @Override
     public String toString()
     {
         return this.version;
     }

     @Override
     public int compareTo(VersionString other)
     {
         if( other == this )
             return 0;
         if( other.version.equals( this.version ) )
             return 0;
         String otherVersionList[] = other.version.split("\\.");
         String thisVersionList[] = this.version.split("\\.");
         int thisIndex = 0;
         for( String otherVersion : otherVersionList )
         {
             if( thisIndex >= thisVersionList.length )
                 break;
             int thisVersionNum =
                     Integer.parseInt( thisVersionList[thisIndex] );
             int otherVersionNum = Integer.parseInt(otherVersion);
             if( thisVersionNum != otherVersionNum )
                 return (thisVersionNum - otherVersionNum < 0) ? -1 : 1;
             thisIndex++;
         }
         if( thisVersionList.length != otherVersionList.length )
             return (thisVersionList.length -
                     otherVersionList.length < 0) ? -1 : 1;
         else
             return 0;
     }

     /**
      * @param args the command line arguments
      */
     public static void main(String[] args) {
         VersionString s10 = new VersionString("10");
         VersionString s10b = new VersionString("10");
         StringBuilder sb = new StringBuilder();
         sb.append("1");
         sb.append("0");
         VersionString s10c = new VersionString( sb.toString() );

         VersionString s10_9 = new VersionString("10.9");
         VersionString s10_8 = new VersionString("10.8");
         VersionString s9 = new VersionString("9");
         VersionString s9_7 = new VersionString("9.7");

         compare( s10, s9 );
         compare( s9, s10 );
         compare( s10, s10 );
         compare( s10, s10b );
         compare( s10, s10c );
         compare( s9, s9 );
         compare( s10, s10_9 );
         compare( s10_9, s10 );
         compare( s10_8, s10_9 );
         compare( s10_9, s10_8 );
         compare( s9_7, s10_8 );
         compare( s10, s9_7 );
         compare( s9_7, s10 );
         try {
             compare( s9_7, null );
         } catch( Exception ex )
             { System.out.println( ex ); }

         construct( null );
         construct( "" );
         construct( "abc" );
         construct( "10.9a" );
         construct( "7.0" );
         construct( "6." );
         construct( ".1" );

     }

     private static void compare( VersionString s1, VersionString s2 ) {
         System.out.print("Compare " + s1 + " and " + s2 + " : ");
         System.out.println( s1.compareTo(s2) );
     }

     private static void construct( String s ) {
         System.out.print("Constructing \"" +s+ "\" - " );
         try {
             new VersionString( s );
         } catch( Exception ex )
             { System.out.print( ex ); }
         finally { System.out.println(""); }
     }
}