I'd like to do the following: I have a simple function written in Clojure/ClojureScript:
(defn add
[a b]
(+ a b))
I want to wrap this function into a Java class and put it in a jar so that I can access it in an existing Java/Android project. My previous approach was to use gen-class and create an uberjar. This however leads to some problems.
As an alternative approach I considered compiling the function using ClojureScript (a solution also suggested by Sam Beran).
So far I understand how to:
compile javascript files into Java classes
put them in a .jar
Compile ClojureScript
I'm not struggling to get the ClojureScript output into a format that can be passed on to the Rhino compiler.
Any thoughts?
IMPORTANT NOTE: I do not want to create a class with a main function as is done here!
One general way of going about this would be to:
At build time:
run the ClojureScript compiler to generate a JavaScript file
put the JavaScript file into the resource directory.
compile the Java class that uses it
make a jar file (an Uberjar or a normal Unterjar)
this Java class should:
make a java class that on initialization start up Rhino
on instantiation runs the javascript from the resource.
On a desktop of server you may not get the same awesome startup times My. Beran reported on android because processes on android have the advantage of starting life with a warmed up runtime with Rhino ready to go from the moment they start (they inherit it from the Zygote process)
Related
I noticed that IntelliJ can parse .kts files as Kotlin and the code editor picks them up as free-floating Kotlin files. You are also able to run the script in IntelliJ as you would a Kotlin file with a main method. The script executes from top to bottom.
This form is PERFECT for the project I'm working on, if only I knew an easy way to use them from within Java or Kotlin.
What's the idiomatic way to "run" these scripts from Java or Kotlin?
Note that script files support in Kotlin is still pretty much experimental. This is an undocumented feature which we're still in the process of designing. What's working today may change, break or disappear tomorrow.
That said, currently there are two ways to invoke a script. You can use the command line compiler:
kotlinc -script foo.kts <args>
Or you can invoke the script directly from IntelliJ IDEA, by right-clicking in the editor or in the project view on a .kts file and selecting "Run ...":
KtsRunner
I've published a simple library that let's you run scripts from regular Kotlin programs.
https://github.com/s1monw1/KtsRunner
Example
The example class
data class ClassFromScript(val x: String)
The .kts file
import de.swirtz.ktsrunner.objectloader.ClassFromScript
ClassFromScript("I was created in kts")
The code to load the class
val scriptReader = Files.newBufferedReader(Paths.get("path/classDeclaration.kts"))
val loadedObj: ClassFromScript = KtsObjectLoader().load<ClassFromScript>(scriptReader)
println(loadedObj.x) // >> I was created in kts
As shown, the KtsObjectLoader class can be used for executing a .kts script and return its result. The example shows a script that creates an instance of the ClassFromScript type that is loaded via KtsObjectLoader and then processed in the regular program.
As of 2020 (Kotlin 1.3.70), you can just use the straightforward
kotlin script.main.kts
Note that using the file extension .main.kts instead of .kts seems to be important.
Note that for me this does not seem to run the main() function if defined, I had to add a manual call to main() at the top level.
One of the advantages of Kotlin script is the ability to declare code and dependencies inside a single file (with #file:DependsOn, see for example here)
early 2020ies kscript that you find at https://github.com/holgerbrandl/kscript
seems to be the most convenient and well supported way to go ...
jgo can fetch and run code from Maven repositories, so can be used to invoke
https://github.com/scijava/scijava-common and https://github.com/scripting-kotlin to execute a local Foo.kt like so:
jgo --repository scijava.public=maven.scijava.org/content/groups/public org.scijava:scijava-common:#ScriptREPL+org.scijava:scripting-kotlin Foo.kt
If no Foo.kt is provided, it launches a Kotlin REPL.
I'm doing some basic java homework for a class on my new laptop - issue is, I can't seem to get the program to compile and run from my batch file using the directions the instructor gave me.
I've set the Path variable to my JDK inside the Environment Variables settings.
My program is a simple shipping program to keep track of shipment information - I have the program working flawlessly in NetBeans (which our instructor advised us to use for developing the code), but he's going to be testing them using batch files, so we're also advised to test them on our systems with one we create prior to turning them in - pretty straightforward.
Issue is, I cannot seem to get this to work. I've never done it before, but I've used .bat files to compile and run C++ programs, as well as using makefiles on a unix system, so I feel like I'm absolutely stupid for not figuring this out on my own, but none of my searches have returned any fruitful solutions that help at all.
My program consists of 3 .java files:
Shipment.java - an interface that contains abstracted methods that are implemented in the ShipmentHW1 class
ShipmentHW1.java - a class that implements the abstracted methods from Shipment and has constructors, etc to create a usable object
TestShipment.java - the main class of this program, which utilizes and creates ShipmentHW1 objects based on preset parameters. This is super duper basic stuff here, and again, it runs perfectly fine inside the NetBeans IDE.
The instructions given to us state to have the batch file inside the package directory (which in this case I've set aside a seperate folder on my desktop titled "shipping", which is the package name - shouldn't be any issues there), where the 3 .java files are located as well.
They say if you don't need to explicitly list the path to the JDK, then you can simply have
javac TestShipment.java
java TestShipment.java
pause
Afterwards I get errors talking about how it "cannot find symbol Shipment s = new ShipmentHW1();"
I've tried adding imports, but since they're in the same package it shouldn't even be an issue.
Directory path is
C:\Users\X\Desktop\shipping
All 7 files are contained within:
TestShipment.java
TestShipment.class
Shipment.java
Shipment.class
ShipmentHW1.java
ShipmentHW1.class
doHW1.bat
Does anyone have any idea? I can provide more information if I've been too vague
Also, I'm on Windows 8 if that makes any difference
Solved
Batch file now reads
javac TestShipment.java Shipment.java ShipmentHW1.java
cd ..
java shipment.TestShipment
pause
and it works like a charm. Anyone have any ideas why I had to call the package.class instead of just compiling it regularly?
Try doing
javac TestShipment.java
java TestShipment
pause
Without seeing the contents of TestShipment.java, I'll assume you have some dependency on the Shipment and ShipmentHW1 classes. As such, when you execute a program that uses the TestShipment class, you need to have the .class files for each of the three (and any other dependencies).
So you will have to compile Shipment.java and ShipmentHW1.java as well before running your java command. If they are in the same package, you're good, if not, you will have to specify an appropriate value for the -cp option.
When running java with a class name, you need to specify the fully qualified class name.
If your .java files are declared to be in the 'shipping' package, then you probably need to be running java from the parent directory of 'shipping', e.g.
cd <path>/shipping
javac TestShipment.java
cd ..
java shipping/TestShipment
I'm attempting to make a game library in Java that uses Lua for the scripts. The real issue appears when I try to require a Java class (that is inside of a jar), and whenever I try to do so, I get an error much like the one below:
Exception in thread "main" org.luaj.vm2.LuaError: #/C:/xampp/htdocs/LevelDesigner/Projects/Lua Test/bin/levels/Test.lua:2 module
'resources.GameLevel' not found: resources.GameLevel
no field package.preload['resources.GameLevel']
How can I require a Java class that is within a jar? Right now it seems that, with Lua, I can only require .lua files, and not .class files. This is obviously problematic as Java files are compiled down to class files...And that is what I need to require.
The answer to this question is to use luajava.bindClass as opposed to require in all of your Lua scripts.
I have an application using Jython 2.1.
In the app I was using jythonc to convert the python scripts to java classes and then include these classes in my webapp like any other.
So I was able to assign package name to python scripts and access these classes like any other java class.
Now I plan to migrate to Jython 2.5. Jython 2.5 has removed support for jythonc.
So I tried to use
jython -m compileall /path/to/my/python/scripts.
When I do that I get all the compiled bytecode files in the same folder. Each of the files have names like myclass$py.class (where my python file is myclass.py).
My questions -
First of all can I access these classes in another normal java
class?
If so, what is the class name I should use ? When I use it like new
myclass() my code does not compile.
Is there a way, I can assign / force a package name or class name
for the generated bytecode with compileall?
Note -
I need to upgrade to jython 2.5 because I need newer versions of
python that it supports.
I would like to stick with pre-compiling the
python code into bytecode, as I want to do optimizations on the
bytecode. So the recommended object factory method is only a
last resort. I am assuming the object factory approach will not allow
me to process the generated bytecode.
Any help is appreciated.
I have a text (.txt) file that contains Java code! I want to create a method that includes this Java code and then call that method through the program.
Can anybody suggest a way to do this?
let consider this example what it does actually load the source code, compile and execute the java code by simpler program by using JavaCompiler API.
Use the JavaCompiler. It can compile code from a String, so I'm sure it could handle code from a text file.
Do you think instead of putting it in the main method I can put it in for example test method and call method like this?
Put it wherever you like. E.G. see the STBC & especially the source code. It provides a GUI and can compile the code in the text area on button click.
this program need tools.jar but jre 7 doesnt have this!!
Did you try reading the documentation that is provided for the STBC? Notably:
System Requirements
STBC will run on any computer with a version 1.6+ Java Plug-In* JDK (AKA SDK).
(*) The API that STBC uses is merely a public interface to the compiler in the tools.jar that is distributed only with JDKs (though the 'public JRE' of the JDK also seems to acquire a tools.jar). This leads to some unusual requirements in running either the native jar, or the web start app.
Or shorter, no JRE will have a JavaCompiler, only JDKs have them.
Change the .txt file to a .java file,
add it to your java project
Compile the code
Execute the methods
Load the file in through standard java IO and then have Groovy evaluate it for you:
http://groovy.codehaus.org/Embedding+Groovy
it's something like quine:
http://www.nyx.org/%7Egthompso/quine.htm