• Will Senn <Will_member pathlink.com> Jun 16 2006
• Scott Michel <scottm aero.org> Jun 19 2006
• Will Senn <Will_member pathlink.com> Jun 19 2006
• Scott Michel <scottm aero.org> Jun 20 2006
• Will Senn <wsenn cc.admin.unt.edu> Jun 21 2006
• Scott Michel <scottm aero.org> Jun 21 2006
• Will Senn <wsenn cc.admin.unt.edu> Jun 22 2006
• Scott Michel <scottm aero.org> Jul 12 2006
• Jan Knepper <jan smartsoft.us> Jun 19 2006

Hi,

I am having trouble building a dll that java can use jni on, seems to build
fine, but then just hangs and hangs and hangs...

Here's the c:
--
-- hello.c
--
#include <jni.h>
#include "HelloWorld.h"
#include <stdio.h>

JNIEXPORT void JNICALL 
Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj) 
{
printf("Hello world!\n");
return;
}

--
-- HelloWorld.h is a generated file (java gen's it)
--
#include <jni.h>
/* Header for class HelloWorld */

#ifndef _Included_HelloWorld
#define _Included_HelloWorld
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class:     HelloWorld
* Method:    displayHelloWorld
* Signature: ()V
*/
JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld
(JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif

Here is the compile command that I gave dmc:
dmc -I C:\jdk1.5.0_07\include;C:\jdk1.5.0_07\include\win32 -mn -WD hello.c
kernel32.lib

There are no errors displayed and a dll is created. However, when I try to do
the java trick (which works with ms compiler created dll's), it hangs. Here's th
e java stuff, in case you want to see :)

--HelloWorld.java
class HelloWorld {
public native void displayHelloWorld();

static {
System.loadLibrary("hello");
}

public static void main(String[] args) {
new HelloWorld().displayHelloWorld();
}
}

compile the java byte code: javac -classpath . HelloWorld.java
generate the HelloWorld.h file: javah -jni -classpath . HelloWorld
compile the dll: dmc -I C:\jdk1.5.0_07\include;C:\jdk1.5.0_07\include\win32 -mn
-WD hello.c kernel32.lib
execute the java app: java -classpath . HelloWorld

Any help would be greatly appreciated.

Thanks,

Will

Wouldn't happen to be doing iostream calls, would you?

Will Senn wrote:
 Hi,
 
 I am having trouble building a dll that java can use jni on, seems to build
 fine, but then just hangs and hangs and hangs...
 
 Here's the c:
 --
 -- hello.c
 --
 #include <jni.h>
 #include "HelloWorld.h"
 #include <stdio.h>
 
 JNIEXPORT void JNICALL 
 Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj) 
 {
 printf("Hello world!\n");
 return;
 }
 
 --
 -- HelloWorld.h is a generated file (java gen's it)
 --
 #include <jni.h>
 /* Header for class HelloWorld */
 
 #ifndef _Included_HelloWorld
 #define _Included_HelloWorld
 #ifdef __cplusplus
 extern "C" {
 #endif
 /*
 * Class:     HelloWorld
 * Method:    displayHelloWorld
 * Signature: ()V
 */
 JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld
 (JNIEnv *, jobject);
 
 #ifdef __cplusplus
 }
 #endif
 #endif
 
 Here is the compile command that I gave dmc:
 dmc -I C:\jdk1.5.0_07\include;C:\jdk1.5.0_07\include\win32 -mn -WD hello.c
 kernel32.lib
 
 There are no errors displayed and a dll is created. However, when I try to do
 the java trick (which works with ms compiler created dll's), it hangs. Here's
th
 e java stuff, in case you want to see :)
 
 --HelloWorld.java
 class HelloWorld {
 public native void displayHelloWorld();
 
 static {
 System.loadLibrary("hello");
 }
 
 public static void main(String[] args) {
 new HelloWorld().displayHelloWorld();
 }
 }
 
 compile the java byte code: javac -classpath . HelloWorld.java
 generate the HelloWorld.h file: javah -jni -classpath . HelloWorld
 compile the dll: dmc -I C:\jdk1.5.0_07\include;C:\jdk1.5.0_07\include\win32 -mn
 -WD hello.c kernel32.lib
 execute the java app: java -classpath . HelloWorld
 
 Any help would be greatly appreciated.
 
 Thanks,
 
 Will
 
 

printf("Hello world!\n");
return;

is the only code in the called dll.


In article <e76k2s$1hb7$1 digitaldaemon.com>, Scott Michel says...
Wouldn't happen to be doing iostream calls, would you?

Will Senn wrote:
 Hi,
 
 I am having trouble building a dll that java can use jni on, seems to build
 fine, but then just hangs and hangs and hangs...
 
 Here's the c:
 --
 -- hello.c
 --
 #include <jni.h>
 #include "HelloWorld.h"
 #include <stdio.h>
 
 JNIEXPORT void JNICALL 
 Java_HelloWorld_displayHelloWorld(JNIEnv *env, jobject obj) 
 {
 printf("Hello world!\n");
 return;
 }
 
 --
 -- HelloWorld.h is a generated file (java gen's it)
 --
 #include <jni.h>
 /* Header for class HelloWorld */
 
 #ifndef _Included_HelloWorld
 #define _Included_HelloWorld
 #ifdef __cplusplus
 extern "C" {
 #endif
 /*
 * Class:     HelloWorld
 * Method:    displayHelloWorld
 * Signature: ()V
 */
 JNIEXPORT void JNICALL Java_HelloWorld_displayHelloWorld
 (JNIEnv *, jobject);
 
 #ifdef __cplusplus
 }
 #endif
 #endif
 
 Here is the compile command that I gave dmc:
 dmc -I C:\jdk1.5.0_07\include;C:\jdk1.5.0_07\include\win32 -mn -WD hello.c
 kernel32.lib
 
 There are no errors displayed and a dll is created. However, when I try to do
 the java trick (which works with ms compiler created dll's), it hangs. Here's
th
 e java stuff, in case you want to see :)
 
 --HelloWorld.java
 class HelloWorld {
 public native void displayHelloWorld();
 
 static {
 System.loadLibrary("hello");
 }
 
 public static void main(String[] args) {
 new HelloWorld().displayHelloWorld();
 }
 }
 
 compile the java byte code: javac -classpath . HelloWorld.java
 generate the HelloWorld.h file: javah -jni -classpath . HelloWorld
 compile the dll: dmc -I C:\jdk1.5.0_07\include;C:\jdk1.5.0_07\include\win32 -mn
 -WD hello.c kernel32.lib
 execute the java app: java -classpath . HelloWorld
 
 Any help would be greatly appreciated.
 
 Thanks,
 
 Will
 
 

Will Senn wrote:
 printf("Hello world!\n");
 return;
 
 is the only code in the called dll.


Ok, so you're only using stdio. Make sure you're using the DLL runtime 
and not the statically linked DMC runtime. Will require a recompile.

Scott Michel wrote:
 Will Senn wrote:
 printf("Hello world!\n");
 return;

 is the only code in the called dll.


 Ok, so you're only using stdio. Make sure you're using the DLL runtime 
 and not the statically linked DMC runtime. Will require a recompile.


Scott,

What do you mean by "DLL runtime and not he statically linked DMC 
runtime"? or rather, how do I ensure that this is the case - is it a 
paramter to the compiler or what?

Thanks,
Will

Will Senn wrote:
 What do you mean by "DLL runtime and not he statically linked DMC 
 runtime"? or rather, how do I ensure that this is the case - is it a 
 paramter to the compiler or what?


"-ND" to the compiler. That causes the compiler to insert a library 
record into the object file that picks up the DLL version of the 
compiler runtime.

http://www.digitalmars.com/ctg/ctg.html will always be your friend.

Scott Michel wrote:
 Will Senn wrote:
 What do you mean by "DLL runtime and not he statically linked DMC 
 runtime"? or rather, how do I ensure that this is the case - is it a 
 paramter to the compiler or what?


 "-ND" to the compiler. That causes the compiler to insert a library 
 record into the object file that picks up the DLL version of the 
 compiler runtime.
 
 http://www.digitalmars.com/ctg/ctg.html will always be your friend.


Hmmm... Seems like this option needs SND.lib, which is purportedly only 
available on the CD, which costs 40+ bucks.

I verified that this works in MS. I downloaded VC++ 2005 Express Edition 
and built the dll using:

cl -IC:\jdk1.5.0_07\include -IC:\jdk1.5.0_07\include\win32 -LD hello.c 
-Fehello.dll

the dll that resulted worked flawlessly with jni...

I would prefer to use Digital Mars, but I'm not excited about paying for 
a CD just to 'see' if my program will compile and run.

Is there not a way to build this incredibly simplistic example of a dll 
using the downloadable version of dmc?

The cl options are:
-I include dir
-LD create dll
-Fe name output executable

That's it, no bizarre options, just build a dll and name it hello.dll.


Thanks,

Will

Will Senn wrote:
 Hmmm... Seems like this option needs SND.lib, which is purportedly only
 available on the CD, which costs 40+ bucks.


<sarcasm>And this is some incredible hardship?</sarcasm>

 I verified that this works in MS. I downloaded VC++ 2005 Express Edition
 and built the dll using:
 
 cl -IC:\jdk1.5.0_07\include -IC:\jdk1.5.0_07\include\win32 -LD hello.c
 -Fehello.dll
 
 the dll that resulted worked flawlessly with jni...
 
 I would prefer to use Digital Mars, but I'm not excited about paying for
 a CD just to 'see' if my program will compile and run.


Sounds like you use DM for a lot more than just this project.

In the past, '-ND' was the way I went about making JNI work. Static
libraries don't work well, esp. stdio or iostreams are involved.

Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

Attached some code I wrote some years ago to export the Window Address 
BooK (WAB) from Java via JNI.

Hope this helps.

Jan



-- 
ManiaC++
Jan Knepper

But as for me and my household, we shall use Mozilla...
www.mozilla.org