I am trying to find the native implementations of Java Robot functions. I found the Windows implementation here. Where can I find the mac and linux versions. I'm mainly trying to find out what it's doing to see how I can implement this functionality myself in C++.
Okay so I did some digging around and found what I was looking for. These may not be the latest versions but the metadata is there.
Linux: awt_robot.c
Mac: CRobot.m
Win: awt_robot.cpp
The source code of this class seems having no any native methods, probably calls are delegated somewhere else. In any case, OpenJDK seems a proper place to search as this is a complete project and not just part that is written in Java.
Related
I'm trying to build an app that takes a screenshot of specific program that's open(an external program, one that I did not code), but my research just keeps pointing me to c++. I was curious if there's a way to do this, or access Windows stuff in general from Java, or if I just need to jump to a scripting language or C. Thank you.
it depends, here is what I found so far.
you can access process names listed on the Task Manager via the Runtime object found here
an explanation on how to use it is on stackoverflow already here.
but you need to know the name of the app you want to find, such as mspaint.exe, msword.exe, myprogram.exe, and so on...
now if you know the executable name, and the application happens to be running, you can use Java's Robot library to get a 'screenshot'. the java API library for Robot is found here and an example of how to use it can be found here. The stackoverflow answer goes into details about using Robot vs another custom tailored approach to just getting a screenshot.
Also note that the pages i linked to are for Java 7, there is also a Java 8 library found here which would be the more current version.
I usually just google "java api X" and whatever I'm looking for.
hope that helps.
I am trying to use Vowpal Wabbit through Java. I have downloaded and successfully compiled the code from GitHub. The command line tool works fine.
After having a quick look at the repository (especially here), I can only assume that using it through Java is supposed to be already possible, and I don't really want to reinvent the wheel.
A wrapper around Vowpal Wabbit that allows use through Java. This wrapper is designed to be self contained. Because
of the use of JNI, a number of platforms are supported in this JAR.
I have added the maven dependency (found here) to my project, but without any kind of document, I don't really know where to start.
I have seen in another question that it seems to be possible to use VW with Java, but the guy only uses Runtime.getRuntime.exec() to call his bash command, and I can't find any documentation about any other way of doing (and there are only 2 questions mixing VW and Java on SO, which doesn't help).
I am new to JNI, so most likely there is something easy that I don't see.
To be perfectly clear, my questions are :
Should I just make a valid vw command and use it through Runtime.getRuntime.exec()? This doesn't seem to be the spirit of JNI, for there is no need for any wrapper/library for this. Plus, this doesn't make it very portable.
Where (the hell) is the (Java API) documentation ?
Any kind of help or guidance would be welcome.
I was one of the two primary authors of the VW JNI wrapper. Since the posting of this question the interface has significantly changed. We now encourage users to compile the native side on their own and provide it on the java.library.path. We have updated the README significantly to show how to use the library from Java.
I totally agree with your criticism that we have not published the Java API. I will work on that the next time I modify this code. In the meantime please feel free to clone the library and run mvn install and you can generate the Java API docs yourself. They should be quite detailed as we spent a lot of effort writing detailed docs.
You may checkout vowpal wabbit JNI wrapper we've built in Indeed: https://github.com/indeedeng/vowpal-wabbit-java.
We wrote integration test that can work as usage examples and we wrote API documentation as well. Check "using the library" section of README.
Hope this will help.
I don't think this adds a lot, but none of the previous answers really provided a clear answer. Like #Macchiatow mentioned, to use the Java wrapper which comes with Vowpal Wabbit, you would:
(on the project root dir) make all java or make java
cd into java and verify the installation with mvn test
you'd then mvn install to have the Java API jarred up and placed in your local maven repository. Supposedly this builds the JNI parts on your machine, so as to fit the C/C++ libraries of your platform if you have the necessary native C/C++ libraries installed and available to the make command.
you'd supposedly be able to include the vowpal package/s from those jars in the build tool used in your own project (ant/maven/boot/leiningen/sbt/etc. as in here).
For more background maybe see the Vowpal Wabbit Java readme. I think what it tries to say there, is that if you want a ready made jar from maven central, you should make sure it's the same vowpal version you're using, but without knowing more I'd guess if you built it like above, you are by definition using the same version.
I've had the above process work off a fresh clone, with Ubuntu 16.04 and Java 8.
This link may be of some help with regards to setting up a JNI wrapper.
I wasn't able to find Java API documentation anywhere, but Java code seems well documented - did you maybe try generating Javadoc yourself from the code?
There is indeed Java JNI wrapper to have a basic access to VW. By basic I mean to teach your model and to predict probability later on. They also provide Python library that can do far more than wrapper for Java. Recently I was forced to expose few more VW methods to Java by extending code provided.
Back to the questions:
Rather use the vw-jni artifact available in central maven repo and clone their code and run make all java. I some cases compiling code yourself will be the only solution, as for example provided artifact won't run on OpenSuse (my case)
Code available pretty straight forward. VWLearners::create is a factory to get an instance of VW from Java.
I want to develop a small Java program using some input like the pen of a Wacom graphictablet and found only the very active JPen project but are there some more possible alternatives without JNI or JNA (without any additional needed dll files), a pure Java implementation?
You can take a look at JTablet. From another SO thread.
It seems JPen moved to GitHub and this might be the best solution at the moment.
The other alternative solutions are not developed and maintained anymore.
https://github.com/nicarran/jpen
Basically, I need to run Groovy Scripts to manipulate Java objects, and GroovyShell / GroovyScriptEngine seems to be the best way to do so. Is it possible to embed Groovy inside a Java App? I tried placing the groovy-all-1.8.2.jar into my Android Java App's libs folder, referenced it then hit compile but I got a bunch of errors.
How do I do this?
I don't believe this will work. Groovy converts scripts to bytecode, and as the Dalvik bytecode is different to the Java bytecode that Groovy expects, I believe it will have problems...
The Discobot from a few years ago has been resurrected though, and great progress is being made so there is hope on the horizon.
But that doesn't help you today...
In near future it will be possible: http://skillsmatter.com/podcast/home/groovy-android/
I have found it recelty.
You can find the solution from http://melix.github.io/blog/2014/06/grooid.html.
Check it http://glaforge.appspot.com/article/groovy-2-3-3-and-groovy-2-4-beta-1-with-android-support too!
Since 09/2011, Discobot seems to be stuck. The last results seem to be : most of it works, but this is very slow.
Groovy 2.0 is out now, and Guillaume Laforge (insider) says it could helps - especially because of the #CompileStatic new feature of Groovy 2.0. Since then, Groovy 2.0.1...2.0.4, it looks that static compilation got a lot of bugfixes.
But for now, on the official website of Groovy, Android is not discussed, nobody seems to really be in charge (see wiki and wiki).
Here is an example of what you are trying to accomplish. https://github.com/melix/grooidshell-example
It is pretty slow since it has to first compile to class files on the android device and then convert them to dex, but it will accomplish what you are looking for.
A better choice for running scripts on Android is SnapScript. It does not rely on Bytecode and is fully supported on Android.
Is it possible to make use of the Open Office spell-checker outside of Open Office for other Java programs?
Walter
We have done exactly that - used the hunspell engine from java. There is a JNA bridge that can be used to invoke hunspell from java. Very nice to use - takes care of loading the appropriate native library from the jar.
The only problem is that the bridge is not updated with the latest hunspell engine - it is at version 1.1.12, and at the time I looked (last year), hunspell was at 1.2.18, which contained fixes we needed. It's not a big deal to build the hunspell libraries and rebuild the JNA wrapper with the latest hunspell engines, although it does involve cross-platform compilation. IIRC we used a windows box and a linux box to rebuild both those platforms (cygwin on windows didn't cut it) and we didn't need the version for OS X. I can let you have what we built if that's useful.
See
Java API for Hunspell
jna.dev.java.net
OpenOffice simply uses hunspell for the spell checking - you should investigate it instead. Its home page mentions the existence of two java interfaces/ports.