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Clojure - compiling project with Java classes that are potentially not available

I am wrapping a java library in Clojure. Depending on the java library version, some classes exist or not, so my library can fail to even compile if it can't find the java classes. My idea was to use Reflector to use the string name of classes.
Example of what I'm trying to do:
(java.time.LocalDateTime/parse "2020-01-01")
would become
(if right-version?
(clojure.lang.Reflector/invokeStaticMethod "java.time.LocalDate" "parse" (into-array ["2020-01-01"]))
This works but is slower by a factor of 20x. Is there a better way to achieve the same? Can I use a macro that will define the correct function at compile time, depending on the version of the underlying library?
Thanks,

I have been using a macro solution to this problem for 6+ years in the Tupelo Library. It allows you to write code like:
(defn base64-encoder []
(if-java-1-8-plus
(java.util.Base64/getEncoder)
(throw (RuntimeException. "Unimplemented prior to Java 1.8: "))))
The macro itself is quite simple:
(defmacro if-java-1-11-plus
"If JVM is Java 1.11 or higher, evaluates if-form into code. Otherwise, evaluates else-form."
[if-form else-form]
(if (is-java-11-plus?)
`(do ~if-form)
`(do ~else-form)))
(defmacro when-java-1-11-plus
"If JVM is Java 1.11 or higher, evaluates forms into code. Otherwise, elide forms."
[& forms]
(when (is-java-11-plus?)
`(do ~#forms)))
and the version testing functions look like
;-----------------------------------------------------------------------------
; Java version stuff
(s/defn version-str->semantic-vec :- [s/Int]
"Returns the java version as a semantic vector of integers, like `11.0.17` => [11 0 17]"
[s :- s/Str]
(let [v1 (str/trim s)
v2 (xsecond (re-matches #"([.0-9]+).*" v1)) ; remove any suffix like on `1.8.0-b097` or `1.8.0_234`
v3 (str/split v2 #"\.")
v4 (mapv #(Integer/parseInt %) v3)]
v4))
(s/defn java-version-str :- s/Str
[] (System/getProperty "java.version"))
(s/defn java-version-semantic :- [s/Int]
[] (version-str->semantic-vec (java-version-str)))
(s/defn java-version-min? :- s/Bool
"Returns true if Java version is at least as great as supplied string.
Sort is by lexicographic (alphabetic) order."
[tgt-version-str :- s/Str]
(let [tgt-version-vec (version-str->semantic-vec tgt-version-str)
actual-version-vec (java-version-semantic)
result (increasing-or-equal? tgt-version-vec actual-version-vec)]
result))
(when-not (java-version-min? "1.7")
(throw (ex-info "Must have at least Java 1.7" {:java-version (java-version-str)})))
(defn is-java-8-plus? [] (java-version-min? "1.8")) ; ***** NOTE: version string is still `1.8` *****
(defn is-java-11-plus? [] (java-version-min? "11"))
(defn is-java-17-plus? [] (java-version-min? "17"))
The advantage of using the macro version is that you can refer to a Java class normally via the symbol java.util.Base64. Without macros, this will crash the compiler for older versions of Java even if wrapped by an if or when, since the symbol will be unresolved before the if or when is evaluated.
Since Java doesn't have macros, the only workaround in that case is to use the string "java.util.Base64"
and then Class/forName, etc, which is awkward & ugly. Since Clojure has macros, we can take advantage of conditional code compilation to avoid needing the powerful (but awkward) Java Reflection API.
Instead of copying or re-writing these functions into your own code, just use put
[tupelo "22.05.04"]
into your project.clj and away you go!
P.S.
You do not need to throw an exception if you detect an older version of Java. This example simply elides the code if the Java version is too old:
(t/when-java-1-11-plus
(dotest
(throws-not? (Instant/parse "2019-02-14T02:03:04.334Z"))
(throws-not? (Instant/parse "2019-02-14T02:03:04Z"))
(throws-not? (Instant/parse "0019-02-14T02:03:04Z")) ; can handle really old dates w/o throwing
...)

I could not tell from your question if your code uses Reflector on every call to the parse method. If so, you could instead define the Method once to use later many times:
(def right-version? true) ; set as appropriate
(def ^java.lang.reflect.Method parse-method
(when right-version?
(.getMethod (Class/forName "java.time.LocalDateTime")
"parse"
(into-array [java.lang.CharSequence]))))
(defn parse-local-date-time [s]
(when parse-method
(.invoke parse-method nil (into-array [s]))))
(parse-local-date-time "2020-01-01T14:30:00")
;; => #object[java.time.LocalDateTime 0x268fc120 "2020-01-01T14:30"]

Call .dll functions using Java

I need to write an application for a client that calls a method from a ".dll" file. The ".dll" file was previously executed manually from an ".exe" GUI but now they want to automate the process.
I never worked with .dll files so everything that I found until now is the result of a complete day of research, I also received a small documentation with this tool:
The interface is an ActiveX DLL which provides two functions (GetUnitInfo and SaveResult).
In the moment I just want to run the "GetUnitInfo" method from the Winwdows command line using RUNDLL32.exe.
This is the documentation for the "GetUnitInfo" method:
The interface for GetUnitInfo is as follows:
Public Function GetUnitInfo( _
ByVal strRequest As String, _
ByRef strUnitInfo As String,
Optional ByVal strStationName As String = "") As Long
Sample calling code can be:
Dim lRet As Long
Dim strXML as String
lRet = GetUnitInfo( _“<?xml version=""1.0"" ?><GetUnitInfo
xmlns=""urn:GetUnitInfo-schema"" SerialNumber=""BD3ZZTC8MA"" />", strXML)
So I tried to run this method with some dummy parameters because the method returns an error if the parameters are not OK. The command:
RUNDLL32.EXE FFTester.dll, GetUnitInfo test1, test2
But I receive this error:
I used "Dependency Walker" to list the functions from the dll file:
But this are all the functions, normally I would expected that also "GetUnitInfo" is listed.
Can somebody help? It is not mandatory to use RUNDLL32.
Later edit:
I want to call this DLL from a tool that is written in JAVA, I tried to use JNA but I failed so I was thinking to call the dll functions from the command line because if this works I can use a process builder to execute the command.

I fixed my problem and I will provide a solution, maybe it will help someone else.
I used com4j library to generate the interfaces for my dll. After this you need to register your DLL otherwise most problely your code will throw an "ComException", you can read more in my second question.
To register a DLL:
C:\Windows\SysWOW64>regsvr32.exe "path to your DLL" for 32 bit DLL
Or
C:\Windows\System32>regsvr32.exe "path to your DLL" for 64 bit DLL
Also depending on your DLL type, 32 or 64 bit, you need to use proper Eclipse/JDK.

Load Custom Fonts in JavaFX + Clojure

As background, I realize there are about 5 other posts on Stack Overflow about this, bur I've looked at the responses and researched this for countless hours with no real solution. Otherwise I wouldn't have posted here.
I'm new to JavaFX, and I like Clojure, so I'm using chrisx's clj-javafx project from Github as a Clojure wrapper for JavaFX. Most operations work great, such as placing components on the scene/stage and styling them with CSS. There's just one issue: I want to import a custom font, and so far I haven't been able to.
I've tried multiple methods. The Java version of the first thing I tried is:
Font.loadFont(<myClass>.class.getResource("mpsesb.ttf").toExternalForm(), 14);
I tried to do that in Clojure using Java interop but I'm not sure how Clojure handles Java classes. Instead I used clojure.java.io.resource:
(use '[clojure.java.io :only [resource]])
(resource "mpsesb.tff")
And it prints the URL of the .ttf file just fine.
Then I tried to use that URL and use it as a parameter in the Font.loadFont method, which didn't work. After playing around with seriously 100 permutations of dot operators and Java methods and classes, I got the following to not print any errors, unlike the other combinations I tried:
(Font/loadFont "fonts/ttf/mpsesb.ttf")
But it just returns nil, which according to the JavaFX API means the font didn't actually load. I even tried fake pathnames and they also returned nil without errors, so the Font/loadFont function seems less promising than I thought.
I finally tried using CSS to load the font instead of using Java to import it:
#font-face {
font-family: 'MyrProSemiExtBold';
src: url('file:/Users/<restOfPath>/mpsesb.ttf');
}
.label {
-fx-font-size: 14px;
-fx-font-weight: normal;
-fx-font-family: 'MyrProSemiExtBold';
}
But no luck. The labels just show up as the default font (Lucida Grande) at 14 pt.
Thank you ahead of time for any suggestions you may have.
EDIT:
Thanks, #jewelsea. The first thing I did after reading what you wrote is get Java 8 + JDK 8 (build b101). I'm using Sublime Text, so I got SublimeREPL to recognize JavaFX using Maven like so in Terminal:
$ mvn deploy:deploy-file -DgroupId=local.oracle -DartifactId=javafxrt -Dversion=8.0 -Dpackaging=jar -Dfile=/System/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/l‌​ib/ext/jfxrt.jar -Durl=file:/Users/vaniificat/.m2/repository
Most of the JavaFX-referent code worked, but now the whole javafx.scene.control package doesn't work, which means no Labels, no Buttons, no TextFields, etc.... :
> (import javafx.scene.control.Button)
: NoClassDefFoundError Could not initialize class javafx.scene.control.Button
java.lang.Class.forName0 (Class.java:-2)
> (import javafx.scene.control.Label)
: NoClassDefFoundError javafx.scene.control.Labeled
java.lang.Class.forName0 (Class.java:-2)
> (import javafx.scene.control.TextField)
: NoClassDefFoundError javafx.scene.control.Control
java.lang.Class.forName0 (Class.java:-2)
> (import '(javafx.scene.control Button Label PasswordField TextField))
: NoClassDefFoundError Could not initialize class javafx.scene.control.Button
java.lang.Class.forName0 (Class.java:-2)
A possible reference to these errors may be found at https://forums.oracle.com/thread/2526150. Basically the gist is that JavaFX 8 is only in beta so we can't expect it to work 100%. Hmm!
I opened an issue on JIRA: https://bugs.openjdk.java.net/browse/JDK-8093894. Once this gets addressed I can more fully explore #jewelsea 's other suggestions.

These are mostly suggestions rather than definitive solutions
On #font-face
Use Java 8 if you can. It has support for the #font-face css notation (which earlier versions of JavaFX such as 2.2 do not). It also has a revamped font system which might be a bit more robust. Because the font face can be loaded via css in Java 8, you may not need to solve your loading resources relative to the class location issue.
On Font.loadFont
You should be able to use the Font.loadFont method as you are trying to use it. JavaFX 2.x has supported custom fonts from it's initial release. There are some steps for loading fonts in JavaFX in plain Java: How to embed .ttf fonts is JavaFx 2.2?. I know you have already looked at that and it hasn't helped - just including it here for reference so that somebody who really knows clojure but not JavaFX may help to troublehoot the issue.
Check that your target font is compatible
Double-check that the particular font that you are using loads and is used in a regular Java based JavaFX application (just to ensure that there is not something incompatible between the font file and the JavaFX system on your platform).
You may need further help
I don't know how loading relative resources works in clojure either (or maybe there is some other issue with your code) - but perhaps a clojure expert can post another answer that allows it to work. You may want to edit your question to include an sscce.

Update: As was pointed out, the original answer did not directly answer the OP's question. I've created a blog post about the original technique in case anyone is interested.
Here is a short program that does what you want.
(ns demo.core
(:gen-class
:extends javafx.application.Application)
(:import
[javafx.application Application]
[javafx.event EventHandler]
[javafx.scene Scene]
[javafx.scene.control Button]
[javafx.scene.layout StackPane]
[javafx.scene.text Font])
(:require [clojure.java.io :as jio]))
(defn- get-font-from-resource
"Load the named font from a resource."
[font-name]
(let [prefix "demo/resources/"
url (jio/resource (str prefix font-name))
fnt (Font/loadFont (.toExternalForm url) 20.0)]
fnt))
(defn -start
"Build the application interface and start it up."
[this stage]
(let [root (StackPane.)
scene (Scene. root 600 400)
fnt (get-font-from-resource "ITCBLKAD.TTF")
btn (Button. "Press Me!")]
(.setOnAction btn
(reify EventHandler
(handle [this event]
(doto btn
(.setText (str "This is " (.getName fnt)))
(.setFont fnt)))))
(.add (.getChildren root) btn)
(doto stage
(.setTitle "Font Loading Demo")
(.setScene scene)
(.show))))
(defn -main
[& args]
(Application/launch demo.core args))
In this project, I placed the font file in resources, a sub-directory of demo - where the Clojure source is stored - hence the "prefix" in the function get-font-from-resource.
It looks like the problem you might have been having with loadFont was in your conversion from the URL to the String form. The external form is an absolute path starting at the root directory on the drive.
Tip: You probably know this, but one thing that continually screws me up are methods in JavaFX that require double parameters, like Font/loadFont. I'm used to Java just promoting integer arguments to double. In Clojure, if you use an integer where a double is required, the program fails with a less than useful error message.

How to write a Ruby-regex pattern in Java (includes recursive named-grouping)?

well... i have a file containing tintin-script. Now i already managed to grab all actions and substitutions from it to show them properly ordered on a website using Ruby, which helps me to keep an overview.
Example TINTIN-script
#substitution {You tell {([a-zA-Z,\-\ ]*)}, %*$}
{<279>[<269> $sysdate[1]<279>, <269>$systime<279> |<219> Tell <279>] <269>to <219>%2<279> : <219>%3}
{4}
#substitution {{([a-zA-Z,\-\ ]*)} tells you, %*$}
{<279>[<269> $sysdate[1]<279>, <269>$systime<279> |<119> Tell <279>] <269>from <119>%2<279> : <119>%3}
{2}
#action {Your muscles suddenly relax, and your nimbleness is gone.}
{
#if {$sw_keepaon}
{
aon;
};
} {5}
#action {xxxxx}
{
#if {$sw_keepfamiliar}
{
familiar $familiar;
};
} {5}
To grab them in my Ruby-App i read my script-file into a varibable 'input' and then use the following pattern to scan the 'input'
pattern = /(?<braces>{([^{}]|\g<braces>)*}){0}^#(?<type>action|substitution)\s*(?<b1>\g<braces>)\s*(?<b2>\g<braces>)\s*(?<b3>\g<braces>)/im
input = ""
File.open("/home/igambin/lmud/lmud.tt") { |file| input = file.read }
input.scan(pattern) { |prio, type, pattern, code|
## here i usually create objects, but for simplicity only output now
puts "Type : #{type}"
puts "Pattern : #{pattern}"
puts "Priority: #{prio}"
puts "Code :\n#{code}"
puts
}
Now my idea was to use the netbeans platform to write a module to not only keep an overview but also to assist editing the tintin script file. So opening the file in an Editor-Window I still need to parse the tintin-file and have all 'actions' and 'substitutions' from the file grabbed and displayed in an eTable, in wich I could dbl-click on one item to open a modification-window.
I've setup the module and got everything ready so far, i just can't figure out how to translate the ruby-regex pattern i've written to a working java-regex-pattern. It seems named-group-capturing and especially the recursive application of these groups is not supported in Java. Without that I seem to be unable to find a working solution...
Here's the ruby pattern again...
pattern = /(?<braces>{([^{}]|\g<braces>)*}){0}^#(?<type>action|substitution)\s*(?<b1>\g<braces>)\s*(?<b2>\g<braces>)\s*(?<b3>\g<braces>)/im
Can anyone help me to create a java pattern that matches the same?
Many thanks in advance for tips/hints/ideas and especially for solutions or (close-to-solution comments)!

Your text format seems pretty simple; it's possible you don't really need recursive matching. This Java-compatible regex matches your sample data correctly, as far as I can tell:
(?s)#(substitution|action)\s*\{(.*?)\}\s*\{(.*?)\}\s*\{(\d+)\}
Would that work for you? If you run Java 7, you can even name the groups. ;)

Can anyone help me to create a java pattern that matches the same?
No, no one can: Java's regex engine does not support recursive patterns (as Ruby 1.9 does).

Problems Calling a Java Class from JRuby

I'm trying to use boilerpipe from JRuby. I've seen the guide for calling Java from JRuby, and have used it successfully with another Java package, but can't figure out why the same thing isn't working with boilerpipe.
I'm trying to basically do the equivalent of this Java from JRuby:
URL url = new URL("http://www.example.com/some-location/index.html");
String text = ArticleExtractor.INSTANCE.getText(url);
Tried this in JRuby:
require 'java'
url = java.net.URL.new("http://www.example.com/some-location/index.html")
text = Java::DeL3sBoilerpipeExtractors::ArticleExtractor.INSTANCE.getText(url)
This is based on the API Javadocs for boilerpipe. Here's the error:
jruby-1.6.0 :042 > Java::DeL3sBoilerpipeExtractors::ArticleExtractor
NameError: cannot load Java class deL3sBoilerpipeExtractors.ArticleExtractor
from org/jruby/javasupport/JavaClass.java:1195:in `for_name'
from org/jruby/javasupport/JavaUtilities.java:34:in `get_proxy_class'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/site_ruby/shared/builtin/javasupport/java.rb:45:in `const_missing'
from (irb):42:in `evaluate'
from org/jruby/RubyKernel.java:1087:in `eval'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:158:in `eval_input'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:271:in `signal_status'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:270:in `signal_status'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:155:in `eval_input'
from org/jruby/RubyKernel.java:1417:in `loop'
from org/jruby/RubyKernel.java:1190:in `catch'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:154:in `eval_input'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:71:in `start'
from org/jruby/RubyKernel.java:1190:in `catch'
from /usr/local/rvm/rubies/jruby-1.6.0/lib/ruby/1.8/irb.rb:70:in `start'
from /usr/local/rvm/rubies/jruby-1.6.0/bin/irb:17:in `(root)'
Looks like it didn't parse the camelcase into the appropriate Java package name. What am I doing wrong? I believe I've set up my classpath alright (last 3 entries), though there may be some conflict with xerces possibly being included twice:
$ echo $CLASSPATH
:/jellly/Maui1.2:/jellly/Maui1.2/src:/jellly/Maui1.2/bin:/jellly/Maui1.2/lib/commons-io-1.4.jar:/jellly/Maui1.2/lib/commons-logging.jar:/jellly/Maui1.2/lib/icu4j_3_4.jar:/jellly/Maui1.2/lib/iri.jar:/jellly/Maui1.2/lib/jena.jar:/jellly/Maui1.2/lib/maxent-2.4.0.jar:/jellly/Maui1.2/lib/mysql-connector-java-3.1.13-bin.jar:/jellly/Maui1.2/lib/opennlp-tools-1.3.0.jar:/jellly/Maui1.2/lib/snowball.jar:/jellly/Maui1.2/lib/trove.jar:/jellly/Maui1.2/lib/weka.jar:/jellly/Maui1.2/lib/wikipediaminer1.1.jar:/jellly/Maui1.2/lib/xercesImpl.jar:/jellly/boilerpipe-1.1.0/boilerpipe-1.1.0.jar:/jellly/boilerpipe-1.1.0/lib/nekohtml-1.9.13.jar:/jellly/boilerpipe-1.1.0/lib/xerces-2.9.1.jar

I'd recommend against trying to guess the module name we put under Java::, since for unusual packages it can get mangled pretty badly. Use java_import 'your.weird.package.ArticleExtractor' or if all the package components are compatible with Ruby method naming, you can also do Java::your.weird.package.ArticleExtractor.
Also, since you might run into this... you'll want to reference the INSTANCE variable as ArticleExtractor::INSTANCE, since we map it as a Ruby constant.
Have fun!

You can also use the nice Jruby Boilerpipe Gem which wraps the Java code
Or the pure ruby implementation of Boilerpipe Ruby Boilerpipe Gem
require 'boilerpipe'
Boilerpipe::Extractors::ArticleExtractor.text("https://github.com/jruby/jruby/wiki/AboutJRuby")