Cannot find external method "..." (must be public) XSLT - xslt

Question

I'm trying to do some operation on dates using XSL. I found a tutorial on IBM developerWorks with this script.
<?xml version="1.0" encoding="utf-8"?>
<xsl:transform
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:date="http://exslt.org/dates-and-times"
version="1.0"
>
<xsl:output method="html"/>
<!-- B -->
<xsl:variable name="now" select="date:date-time()"/>
<xsl:template match="/">
<!-- The rest of the Web site HTML material would go here -->
<xsl:call-template name="date-section"/>
</xsl:template>
<xsl:template name="date-section">
<p>This page was loaded at <xsl:text/>
<!-- C -->
<xsl:value-of select="concat(date:hour-in-day($now), ':',
date:minute-in-hour($now), ':',
date:second-in-minute($now))"/>
<xsl:text> on </xsl:text>
<xsl:value-of select="concat(date:day-in-month($now), ' ',
date:month-name($now), ' ',
date:year($now))"/>
</p>
<p>
<!-- D -->
<xsl:variable name="days-elapsed"
select="concat('-P',date:day-in-month($now),'D')"/>
<xsl:variable name="one-month-hence"
select="date:add($now, 'P1M')"/>
<xsl:variable name="next-month-start"
select="date:add($one-month-hence, $days-elapsed)"/>
<xsl:variable name="seconds"
select="date:seconds(
date:difference($now, $next-month-start)
)"/>
<xsl:text>The next month starts in </xsl:text>
<xsl:value-of select="$seconds div (3600*24)"/>
<xsl:text> days</xsl:text>
</p>
</xsl:template>
I get the following errors:
[ERROR]: Cannot find external method 'com.sun.org.apache.xalan.internal.lib.ExsltDatetime.add' (must be public).
[ERROR]: Cannot find external method 'com.sun.org.apache.xalan.internal.lib.ExsltDatetime.difference' (must be public).
[ERROR]: Cannot find external method 'com.sun.org.apache.xalan.internal.lib.ExsltDatetime.seconds' (must be public).
[ERROR]: Cannot convert data-type 'void' to 'real'.
[FATAL]: Could not compile stylesheet
Any ideas how to fix it. I'm using IntelliJ to run the xsl.
Ultimately I want to to be able to add days to a date. For some reason when I try to use xsl 2 date functions it just tells me they do not exist(And yes I do change the header to version 2 :) ). So I'm trying to make it work with a 3rd party library. The date-time() function from the http://exslt.org/dates-and-times namespace is working but I can't seam to be able to call other functions form that namespace.

Answer 1

the question is a bit old but the answers were, IMHO, not quite correct and my answer might help some other people stumbling upon this thread (as I just did):
The functions used are XSLT 1.0 extension functions, there are different modules (e.g. dates-and-times), each with mandatory and optional functions (and elements). See EXSLT
The issue here is that XALAN does support the module dates-and-times, but not all optional functions.
As suggested, you can surely try to find a "better" XSLT-Processor, but it might require some work to integrate. I personally use on the Linux command line xsltproc, which supports more of the dates-and-times module (try xsltproc --dumpextensions | sort for an overview).
Alternatively, you could try the approach describing how to get current date and time in XSLT 1.0. I haven't tried it myself yet (as said, xsltproc is a good enough workaround), but using a similar approach you should be able to implement what you need without having to touch your tool/java code.
For sake of completeness, my tool with the same problem is Freeplane from freeplane.org, which also uses XALAN (I guess that it's part of standard Java libraries) and fails on similar dates-and-times functions.
Hope this helps,
Eric

Answer 2

I don't know Xalan, so I don't know why it's failing to find these methods.
But if you want to use the XSLT 2.0 date/time functions, you need to invoke an XSLT 2.0 processor, and the obvious one for the Java environment is Saxon (current version is 9.4). Switching processor requires a little bit more than changing the version number: for example, if you are running it from the command line then you will need to use a different command.