How to call c++ functionality from java

Question

I have a Java program that is mostly GUI and it shows data that is written to an xml file from a c++ command line tool. Now I want to add a button to the java program to refresh the data. This means that my program has to call the c++ functionality.

Is the best way to just call the program from java through a system call? The c++ program will be compiled for mac os and windows and should always be in the same directory as the java program.

I would like to generate an executable can the c program be stored inside the jar and called from my program?

Answer 1

If you have access to the code and want an 'interactive' experience with the external program (e.g., make call, get results, make additional calls), investigate JNI, which allows you to call C or C++ code from a Java application by including & linking JNI juice to your C or C++ app with .

See:

http://en.wikipedia.org/wiki/Java_Native_Interface

http://www.acm.org/crossroads/xrds4-2/jni.html

If you really just need a "launch app and get results" sort of solution, check out Runtime.exec(), which lets you launch an external program & capture its output.

See: http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html?page=1

http://www.rgagnon.com/javadetails/java-0014.html

Answer 2

Assuming no better communication method is available (SOAP, ICE, Sockets, etc), I'd call the executable using Runtime.exec(). JNI can be used to interface directly, but I wouldn't recommended it. No you can't put an executable in the jar. Well you can, but you can't run it, since the shell doesn't know how to run it.