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Re: JNI return jobjectArray

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On 30/09/12 21:23, Philipp Kraus wrote:
> class myclass {
>
>    void native mymethod( Double[] x )
> }

I realise this snippet could be just for illustration, but 'native' must 
come before the return type in real code.  Missing semicolon too.

> so the parameter x should be a call-by-reference, I would set x in the 
> native JNI function:
>
> void mymethod( JNIEnv *jenv, jclass jcls, jobjectArray& jarg )

When I tried the class (after the fixes) with javah, I got this:

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class myclass */

#ifndef _Included_myclass
#define _Included_myclass
#ifdef __cplusplus
extern "C" {
#endif
/*
  * Class:     myclass
  * Method:    mymethod
  * Signature: ([Ljava/lang/Double;)V
  */
JNIEXPORT void JNICALL Java_myclass_mymethod
   (JNIEnv *, jobject, jobjectArray);

#ifdef __cplusplus
}
#endif
#endif

The jobjectArray parameter has no '&'.  If it had one, it would not be 
possible to link it with a C implementation.  If an '&' is inserted 
manually, and the function is implemented in C++, the machine code would 
likely be identical to an equivalent function using a pointer, but the 
JVM would not pass a jobjectArray* to it, and you'd get undefined behaviour.


-- 
ss at comp dot lancs dot ac dot uk

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JNI return jobjectArray Philipp Kraus <philipp.kraus@flashpixx.de> - 2012-09-30 22:23 +0200
  Re: JNI return jobjectArray markspace <-@.> - 2012-09-30 14:56 -0700
    Re: JNI return jobjectArray Philipp Kraus <philipp.kraus@flashpixx.de> - 2012-10-01 00:23 +0200
      Re: JNI return jobjectArray markspace <-@.> - 2012-09-30 19:21 -0700
        Re: JNI return jobjectArray Lew <lewbloch@gmail.com> - 2012-09-30 21:14 -0700
          Re: JNI return jobjectArray markspace <-@.> - 2012-10-01 08:32 -0700
      Re: JNI return jobjectArray "Chris Uppal" <chris.uppal@metagnostic.REMOVE-THIS.org> - 2012-10-01 09:39 +0100
  Re: JNI return jobjectArray Roedy Green <see_website@mindprod.com.invalid> - 2012-10-01 10:21 -0700
  Re: JNI return jobjectArray Steven Simpson <ss@domain.invalid> - 2012-10-01 23:46 +0100

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