Is it possible to call java function from Qt Application and if so, how? Do I need to update java source for such task? I have Qt Desktop Opensource edition.
First of all think twice before calling java from C/C++. For Android it allow you call some API function of OS, but you pay with perfomance and some hard catching errors.
Qt designed pretty easy way for calling Java: package - androidextra
But if you need call it on desktop there is a way to avoid it: JNI(as Nejat says).
Here is simple example of using it:
http://www.codeproject.com/Articles/22881/How-to-Call-Java-Functions-from-C-Using-JNI
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How can I bind Qt with java by java java native interface?
I want to make an java app but for UI i want to use Qt, for some reason I can not use qt-jambi so I need to bind Qt with java.
Is it possible to create an Qt app in Qt creator and bind this component to java through java native interface?
If some one knows How qt-jambi works, please tell me, so help!
In fact my general question is that how (if its possible) to make a java app that some of its component like UI is written in c++? I do not want to use only one c++ method or library, I want to use I complete c++ qt app.
Thank you!
sorry for bad english.
When you want to have a hybrid Qt/Java application in which you use Qt API in Java code, definitely the best option is to use Qt Jambi. JNI only lets you to call some Java function from C++ world or vice-versa.
Qt Jambi enables you to to write software in Java in the speed of natively executable code and with native look and feel on different supported platforms. Actually it is a Java binding to Qt, so you can easily use Qt API in Java. There are some documentations on the web about it like this or that.
This may be a bit of an odd question, but I would like to know if you can use Java inside c++14. I don't really care for GTK (I find it confusing and over complicated). Swing, however, is very easy to use, and you can get a working project very quickly. So I would like to know if you can use Java Swing inside c++, so I can use Swing as the foreground, as in what you see like graphics, and use c++ for the background, as in stuff you cant see, like calculations and objects and stuff. So if I can have c++ code tell Swing what to look like, or when to update, that would be very useful for the project I have in mind. Thanks in advance for any advice I may receive.
EDIT: Being able to use c++14 inside Java would be acceptable as well. Also, if anyone could get me example code also, this would be very helpful. Thanks!
You shouldn't run Java from C++, but rather C++ from Java. Oracle gives you a way to load native shared libraries, using JNI.
So you would create your view in Java, using Swing, then you would update your view by calling C++ functions that were pre-compiled and exported in a shared library.
That said, using JNI is quite tricky and the speed improvements of C++ might not be worth it; so you should consider using only Java (or only C++ and a library to create your GUI, such as Qt)
In which direction you go is a matter of taste (loading the JVM from a C++ program or loading DLLs from the JVM side).
Usually you go the way which is more logical, e.g. if you already have a C++ program you likely want to load the JVM from the C++ side. That would be your case. Especially if the Java you want to add is essentially "scripting" the C++ application.
If you already have a Java program and want to access a C++ DLL, you load the DLL from Java and write a simple JNI / native Java class.
In our times you would use tools like JNA for that (instead of JNI): https://github.com/java-native-access/jna
Or you can use SWIG to generate wrappers for your C++ classes: http://www.swig.org/
I have somoe C# source code that I want to be available for java applications under linux OS.
How can I call some C# method from java code?
I have found http://www.mono-project.com/Java but this looks like writing java code in .net environment. It is not what I look for. Rather I need to create new java library that will expose all functionality from C# code, the new library must be executed in pure java environment. Maybe that is possible with IKVM I am not sure.
Use Mono to compile your C# classes on the Linux platform of your choice;
Use JNI to write a set of facade classes between your java code and the compiled C# code.
The closest tool I can find that might be useful would be JNI4Net
I think you would still need Mono to run a .net framework on Linux as well.
Your question is going to be closed (I voted too) simply because it would finally lead to a tool recommendation.
Your best approach is to rewrite them in Java. Or alternatively, there are existing tools (commercial or free) to convert C# to Java,
CSharpJavaMerger Framework
RemObjects C# who compiles C# to JVM.
and many others
Mono is not something you should consider at this moment. Yes, IKVM.NET only helps running Java code on Mono/.NET, and it won't help you in your case.
It's not clear if you can execute the c# project or not through mono, if you can, then process intercomunication is the way to go.
If you are doing it in Linux I should use a pipe channeling to intercomunicate both processes, works really well and is easy to use.
If you can't execute the c# process, then that's another history, you cannot call directly a .net assembly from java.
And also, using mono on Linux per today gives great results (except for ASP .net), we are using it and are getting really good results (faster responses than Java in most scenarios).
I have a java code and created a jar file.
I need to create an Qt application. Can I use this code in that application?
Please help me how can i use that jar file.
Thanks,
Nagaraju.
You could take a look at the capabilities of GCC/GCJ (see http://gcc.gnu.org/ ). IF it's a good idea is a whole other story, and depends on what you have, and what you're trying to accomplish. It should be doable to link SO's created with GCJ in QT applications, but I seriously wonder if you are not better off using either C++ or Java, but not mixing them
If your Java code takes input from stdin or some file and writes output to stdout or some file, then the easiest way is to fork java to run that jar, and parse the output in your Qt code.
Things other than that, you'll need to be a bit specific. Something like "my Java code does painting the screen".
My advice is to use SWT or Swing.
You can use gcj gcj to compile the java code to library and simply call the functions of the java code from your C code.
Yes, you can use your jar file in your Qt application. I've done exactly this myself.
One way is to use the JNI Invocation API. This is part of the Java Native Interface (JNI), which makes it feasible but not pleasant to access Java APIs from C++.
A much more pleasant approach is to use CodeMesh JunC++ion, which wraps the Java APIs in C++ classes. This is a great product, if you can afford it.
If you have very little Java code, it may be easier to port it to C++.
Is there a java api similar to RAPI? I want to be able to access files on the windows mobile device using a java desktop program.
Thanks.
You could use RAPI itself, and access it from Java using JNI or a wrapper like Swig
We were also looking for a similar API in Java but unfortunately none is available. I wrote my own RAPI wrapper using JNI and used that in my program.
The main problem with JNI is that any un-handled exceptions/faults cause the calling Java program to shutdown as well. Do keep that in mind when writing your wrapper. There are different approaches to safe guard these, the simplest and common approach is to write a standalone program written in .Net/C++ that communicates with the RAPI and your Java program communicates with that program using pipes/files etc. this way you also don't have to write a JNI wrapper :-)