asked on

How to throw Exceptions in JNI

Hello all,

How to throw Exceptions in JNI??

class TestException
{
      public native String getFileType(String magicFile,String strFile)throws Exception;
      public static void main(String[] args)
      {
            System.out.println("Hello World!");
      }
}

javah generated code

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

#ifndef _Included_TestException
#define _Included_TestException
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: TestException
* Method: getFileType
* Signature: (Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;
*/
JNIEXPORT jstring JNICALL Java_TestException_getFileType
(JNIEnv *, jobject, jstring, jstring);

#ifdef __cplusplus
}
#endif
#endif

JNIEXPORT jstring JNICALL Java_TestException_getFileType
(JNIEnv *env, jobject object , jstring str1, jstring str2)
{
//some blah blah blah

//now assume exception raised here. then how should c source should return exception object to JVM.
}

Thanks and Best Regards
Sudhakar

ASKER CERTIFIED SOLUTION

girionis

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sudhakar_koundinya

ASKER

thanks. take ur A

expertmb

http://java.sun.com/docs/books/tutorial/native1.1/implementing/error.html

expertmb

oooooooooopss!!!
forgot to reload the question

girionis

Thank you for accepting, glad I was of help :)

sudhakar_koundinya

ASKER

girionis

one quick question

after throwing error if i don't return anything JVM is raising exception. Is it must to return some thing
if(strlen(getError())>0)
      {
            jclass excCls = (*env)->FindClass(env,"java/lang/Exception");
            if (excCls != 0)
            {
                  (*env)->ThrowNew(env, excCls, getError());
                  return ""; //ok ->Is this must here??
                  //return ""; //not ok
            }
      }

girionis

Are you calling it from a C function that returns something? If yes then I'd expect that you need to return something anyway.

sudhakar_koundinya

ASKER

ok, I understand that

Thanks for nice links :-)

girionis