Re: IE opening .jnlp file - JRE version problem

From:
Roedy Green <see_website@mindprod.com.invalid>
Newsgroups:
comp.lang.java.programmer
Date:
Sat, 18 Apr 2009 17:07:38 -0700
Message-ID:
<pkqku49u2ug8kg6g7o81g0vn6qdc2mushc@4ax.com>
On Fri, 17 Apr 2009 21:35:38 -0400, Lew <noone@lewscanon.com> wrote,
quoted or indirectly quoted someone who said :

I have
$ java -version
java version "1.6.0_13"
Java(TM) SE Runtime Environment (build 1.6.0_13-b03)
Java HotSpot(TM) 64-Bit Server VM (build 11.3-b02, mixed mode)


that is the latest official version. It is not a beta.

I think this bit of code to take apart java version numbers might help
you understand how they work.

/*
 * @(#)VersionCheck.java
 *
 * Summary: Check that Java version is sufficiently recent
 *
 * Copyright: (c) 1997-2009 Roedy Green, Canadian Mind Products,
http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any
purpose but military.
 * see http://mindprod.com/contact/nonmil.html
 *
 * Created with: IntelliJ IDEA IDE.
 *
 * Version History:
 * 1.0 1997-03-23 - initial.
 * 1.1 1998-11-10 - add dates
 * 1.2 1998-12-14 - add isJavaVersionOK
 * 1.3 1999-08-24 - add leftPad, rightPad, smarter rep.
isJavaVersionOK now handles 1.3beta.
 * 1.4 2002-08-17 - add quoteSQL
 * 1.5 2005-07-14 - split off from Misc, allow for compilation with
old compiler.
 * 1.7 2006-03-04 - reformat with IntelliJ, provide Javadoc
 */

package com.mindprod.common11;

import java.awt.Color;
import java.awt.Container;
import java.awt.TextArea;

/**
 * Check that Java version is sufficiently recent
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.7 2006-03-04 -
 *
 */

public final class VersionCheck
    {
    // ------------------------------ FIELDS
------------------------------

    /**
     * true if you want extra debugging output and test code
     */
    static final boolean DEBUGGING = false;
    // -------------------------- PUBLIC STATIC METHODS
--------------------------

    /**
     * Ensures Java runtime version e.g. 1.1.7 is sufficiently recent.
Based on code by Dr. Tony Dahlman
     * <adahlman@jps.net>
     *
     * @param wantedMajor java major version e.g. 1
     * @param wantedMinor Java minor version e.g. 1
     * @param wantedBugFix Java bugfix version e.g. 7
     *
     * @return true if JVM version running is equal to or more recent
than (higher than) the level specified.
     */
    public static boolean isJavaVersionOK( int wantedMajor,
                                           int wantedMinor,
                                           int wantedBugFix )
        {
        try
            {
            try
                {
                // java.version will have form 1.1.7A, 11, 1.1., 1.1,
1.3beta,
                // 1.4.2_05 or 1.4.1-rc
                // It may be gibberish. It may be undefined.
                // We have do deal with all this malformed garbage.
                // Because incompetents run the world,
                // it is not nicely formatted for us in three fields.
                String ver = System.getProperty( "java.version" );

                if ( ver == null )
                    {
                    return false;
                    }

                ver = ver.trim();

                if ( ver.length() < 2 )
                    {
                    return false;
                    }

                int dex = ver.indexOf( '.' );

                if ( dex < 0 )
                    {
                    // provide missing dot
                    ver = ver.charAt( 0 ) + '.' + ver.substring( 1 );
                    dex = 1;
                    }

                int gotMajor = Integer.parseInt( ver.substring( 0, dex
) );
                if ( DEBUGGING )
                    {
                    System.out.println( "major:" + gotMajor );
                    }
                if ( gotMajor < wantedMajor )
                    {
                    return false;
                    }
                if ( gotMajor > wantedMajor )
                    {
                    return true;
                    }

                // chop off major and first dot.
                ver = ver.substring( dex + 1 );

                // chop trailing "beta"
                if ( ver.endsWith( "beta" ) )
                    {
                    ver = ver.substring( 0, ver.length() -
"beta".length() );
                    }
                // chop trailing "-rc"
                if ( ver.endsWith( "-rc" ) )
                    {
                    ver = ver.substring( 0, ver.length() -
"-rc".length() );
                    }
                // chop any trailing _nn
                dex = ver.lastIndexOf( '_' );
                if ( dex >= 0 )
                    {
                    ver = ver.substring( 0, dex );
                    }
                // chop any trailing letter as in 1.1.7A,
                // but convert 1.1.x or 1.1.X to 1.1.9
                char ch = ver.charAt( ver.length() - 1 );
                if ( !Character.isDigit( ch ) )
                    {
                    ver = ver.substring( 0, ver.length() - 1 );
                    if ( ch == 'x' || ch == 'X' )
                        {
                        ver += '9';
                        }
                    }
                // check minor version
                dex = ver.indexOf( '.' );
                if ( dex < 0 )
                    {
                    // provide missing BugFix number as in 1.2 or 1.0
                    ver += ".0";
                    dex = ver.indexOf( '.' );
                    }

                int gotMinor = Integer.parseInt( ver.substring( 0, dex
) );
                if ( DEBUGGING )
                    {
                    System.out.println( "minor:" + gotMinor );
                    }
                if ( gotMinor < wantedMinor )
                    {
                    return false;
                    }
                if ( gotMinor > wantedMinor )
                    {
                    return true;
                    }
                // was equal, need to examine third field.
                // check bugfix version
                ver = ver.substring( dex + 1 );
                int gotBugFix = Integer.parseInt( ver );
                if ( DEBUGGING )
                    {
                    System.out.println( "bugFix:" + gotBugFix );
                    }
                return ( gotBugFix >= wantedBugFix );
                }
            catch ( NumberFormatException e )
                {
                if ( DEBUGGING )
                    {
                    System.out.println( "number format" +
e.getMessage() );
                    }
                return false;
                }// end catch
            }
        catch ( StringIndexOutOfBoundsException e )
            {
            if ( DEBUGGING )
                {
                System.out.println( "out of bounds:" + e.getMessage()
);
                }

            return false;
            }// end catch
        }// end isJavaVersionOK

    /**
     * use in a paint routine if Java version is not ok, usually
tested statically.
     *
     * @param wantedMajor java major version e.g. 1
     * @param wantedMinor Java minor version e.g. 1
     * @param wantedBugFix Java bugfix version e.g. 7
     * @param container container to add an error message
component.
     *
     * @return true if version is ok
     */
    public static boolean isJavaVersionOK( int wantedMajor,
                                           int wantedMinor,
                                           int wantedBugFix,
                                           Container container )
        {
        if ( isJavaVersionOK( wantedMajor, wantedMinor, wantedBugFix )
)
            {
            return true;
            }
        else
            {
            String error =
                    "Error: You need Java "
                    + wantedMajor
                    + "."
                    + wantedMinor
                    + "."
                    + wantedBugFix
                    + " or later to run this Applet.\n"
                    + "You are currently running under Java "
                    + System.getProperty( "java.version" )
                    + ".\n"
                    + "Get the latest Java from
http://java.com/en/index.jsp";
            TextArea complain =
                    new TextArea( error, 3, 42,
TextArea.SCROLLBARS_NONE );

            complain.setEditable( false );
            complain.setBackground( Color.white );
            complain.setForeground( Color.red );
            complain.setSize( 300, 50 );
            container.setLayout( null );
            container.add( complain );
            System.err.println( error );
            return false;
            }
        }

    // --------------------------- CONSTRUCTORS
---------------------------

    /**
     * VersionCheck contains only static methods.
     */
    private VersionCheck()
        {

        }
    }
--
Roedy Green Canadian Mind Products
http://mindprod.com

Now for something completely different:
http://www.youtube.com/watch?v=9lp0IWv8QZY

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