Easy JNI Question
Hi,
I am new to using the JNI, and am in the process of implementing it for my C++ app... I can't find any information, however, on what to do with the jint, jfloat, etc. variables.
For example, if I receive a jint with a value of 56, and I want to save that in a regular c++ int in my program - do I have to do anything special, or can I just pass the value straight into it... What about the other way round? How do I convert a c++ int into a jint for return to Java?
Thanks a lot!
Crispin
[524 byte] By [
ddanooa] at [2007-11-26 18:28:26]
# 1
Please read chapter 3 and 4 at http://java.sun.com/docs/books/jni/download/jni.pdf
jint can be used as int in C. However, if you have C++ aplications, you need to write C codes as bridage between your java classes and C++ apps based on my understanding.
Message was edited by:
CIIT_JAVA_Application
# 2
Thanks for the reply... by the way, as far as the 1 or 2 functions I have looked at, c++ versions exist (though the syntax is slightly different).
Another, slightly more technical question:
If I call a method in C++ from Java, how does the threading situation work? Does it open up a new thread in c++? In other words, if I call main() from a JNI function, is it opening it in a standard c++ thread? If I then call another JNI function does it block the thread that main is now running in?
Cheers,
Crispin
# 4
Thanks for the reply bschauwejava
I read the pdf on the JNI, but it doesn't tell me much about casting variables... Would I be right to assume that you turn a c++ int into to a jint like this:
int a = 6;
jint b = (jint)a;
and a jint into a c++ int like this:
jint a = 6;
int b = (int)a;
Thanks!
Crispin
