Calling Java method from C?

[paolobolzoni]

Is it possible to call a Java method from C code?
In the project I am working on, some calculation are made in C code and I would like to call the Java logger to give info about how it is going.

I sought around and I read this:

""You can.[Call a Java method from C] With a callback class that corresponds to a function pointer on the C side. void register_callback(void (*)(const int)); would be mapped to public static native void register_callback(MyCallback arg1); where MyCallback is an interface extending com.sun.jna.Callback with a single method void apply(int value);""

Unfortunately I do not have much experience with Java (I am the one writing in C) and I did not understand much. It seems there is way to treat a Java method as a function pointer, it would be great.
Can anyone explain how-to, or point me to the manual?
Thanks

[twall]

Please take this discussion to the mailing list, not the issues list.

Presumably you're running some Java code already in order to have a "logger". Have that call make a call to your C code to provide it a function, say "void register_callback(void (logger)(const char))". Map that function using JNA, e.g.

interface LoggerCallback extends Callback {
     public void invoke(String msg);
}
void register_callback(LoggerCallback cb);

LoggerCallback c = new LoggerCallback() {
    public void invoke(String msg) {
        // TODO send message on to java logger
    }
};
lib.register_callback(c);

Closes #235.

On May 24, 2013, at 11:55 AM, Paolo Bolzoni wrote:

Is it possible to call a Java method from C code?
In the project I am working on, some calculation are made in C code and I would like to call the Java logger to give info about how it is going.

I sought around and I read this:

""You can.[Call a Java method from C] With a callback class that corresponds to a function pointer on the C side. void register_callback(void (*)(const int)); would be mapped to public static native void register_callback(MyCallback arg1); where MyCallback is an interface extending com.sun.jna.Callback with a single method void apply(int value);""

Unfortunately I do not have much experience with Java (I am the one writing in C) and I did not understand much. It seems there is way to treat a Java method as a function pointer, it would be great.
Can anyone explain how-to, or point me to the manual?
Thanks

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