How to call a C function calling a Java Method from another C function ?

Hi everyone,
I'm just starting to learn JNI and my problem is that I don't know if it is possible to call a C function calling a Java Method (or doing anything else with JNI) from another C function.
In fact, after receiving datas in a socket made by a C function, I would like to create a class instance (and I don't know how to do it too ; ) ) and init this instance with the strings I received in the socket.
Is all that possible ?
Thank you very much for your help !

Hard to understand the question, but by most interpretations the answer is going to be yes.
You do of course understand that JNI is the "API" that sits between Java and C and that every call between the two must go through that. You can't call it directly.

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Does any one have an example of code.
Thinks in advance

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
<html>
<head>
<title> Test server-side JS </title>
</head>
<body>
<script type="text/javascript">
function checkIt(variable, value)
var newScript = "cgi-bin/validateJS.cgi?"+variable+"="+value;
var body = document.getElementsByTagName('body').item(0)
var scriptTag = document.getElementById('loadScript');
if(scriptTag) body.removeChild(scriptTag);
script = document.createElement('script');
script.src = newScript;
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<p>Test.</p>
<form id="f1" action="">
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</html>
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Hi Sunil,
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Jdev 11.1.1.3.0
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How do you call a method from another class without extending as a parent?

How do you call a method from another class without extending it as a parent? Is this possible?

Why don't you just create an instance of the class?
Car c = new Car();
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Is that what you were asking or am I totally misunderstanding your question?
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How to call java method from C ?

Hello,
I try to call a native method from java which calls java method from the same class. Exception (noSuchMethodError) is thrown. Any ideas?
Thanx in advance !
here is the source of the native method :
JNIEXPORT jint JNICALL Java_TestDll_Proc_1Mul_1Int_1Var_1Var_1Stdcall (JNIEnv * env, jclass jcl, jint jarg1, jint jarg2) {
int arg1;
int arg2;
int arg3;
jint res;
char * ch = "test";
jfieldID fid;
jmethodID mid;
int (* procedure) (int *, int * ,int *);
int mch;
arg1 = (int )jarg1;
arg2 = (int )jarg2;
procedure = GetProcAddress(libraryHandle,"Proc_Mul_Int_Var_Var_Stdcall");
procedure(&arg1,&arg2,&arg3);
res = (jint) arg3;
printf("(*env)->GetMethodID(env, jcl, \"test\", \"()V\");\n");
mid = (*env)->GetMethodID(env, jcl, "test", "()V");
printf("(*env)->CallVoidMethod(env, jcl, mid);\n");
(*env)->CallVoidMethod(env, jcl, mid);
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here is the source of the java file:
public class TestDll {
static {
System.loadLibrary("testdllwrap");
System.out.println("java: Library testdllwrap.dll loaded");
public TestDll() {
public native int Proc_Mul_Int_Var_Var_Stdcall(int jarg1, int jarg2);
public void test() {
System.out.println("java: test()");
public static void main(String[] args) {
TestDll access = new TestDll();
int a = 5;
int b = 6;
int c = 0;
System.out.println("Calling Proc_Mul_Int_Var_Var_Stdcall");
c = access.Proc_Mul_Int_Var_Var_Stdcall(a,b);
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Something is wrong with the code you posted here.
Since your native method is not static, it should have the jobject instance as a parameter in the function prototype, not a jclass. Also, you should be calling CallObjectMethod with a jobject, not jclass.
Check out Jace at http://jace.reyelts.com/jace.
To call the java method you would do:
JNIEXPORT jint JNICALL Java_TestDll_Proc_1Mul_1Int_1Var_1Var_1Stdcall
(JNIEnv * env, jobject jTestDll, jint jarg1, jint jarg2) {
TestDll testDll( jTestDll );
testDll.test();
}God bless,
-Toby Reyelts

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hi everyone
i need a help in calling Java method from a javaScript method
ex:
function confirmAddRecord() {
cHours =document.getElementById('frmP:ChargeHours').value;
cSTime =document.getElementById('frmP:ChargeStartTime').value;
var answer = confirm("Are you sure you want to add Record?")
if (answer){
here i want to call the Java Method that is located in session bean that takes the upper params cHours & cSTime
else{
return false;
i know i can do it as an action button but it is required me to be in that way can any one help plz
Message was edited by:
casper77

That depends on the nature of your parameters. I guess you calculate the params on client and then want to submit them. In this case and if you don't want to use Ajax simple add some <input type="hidden"> elements (of course there correspondend components dependent of your framework) and store the params there. If the javascript isn't invoked by a button click, you can use a button nevertheless. Set visible="false" and call
document.getElementById('client_id_of_my_hidden_button').click();
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Here's one I wipped up in 10 minutes... Cool!
package forums;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import krc.utilz.io.Filez;
import java.io.FileNotFoundException;
class FileDisplayer extends JFrame
private static final long serialVersionUID = 0L;
FileDisplayer(String filename) {
    super(filename);
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      text.setText(e.toString());
    this.add(text);
public static void main(String args[]) {
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Filez.read
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   * @param String filename - the name of the file to read
   * @return the contents filename
public static String read(String filename) throws FileNotFoundException {
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   * @param java.io.Reader reader - a subclass of Reader to read from.
   * @return the whole contents of the given reader.
public static String read(Reader in) {
    try {
      StringBuffer out = new StringBuffer();
      try {
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        while( (n=in.read(bfr,0,BFRSIZE)) > 0 ) {
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Problem calling java method from c

Hi ,
I'm trying to call a java method from a C program. it gives no error during compilation as well as building the application. but when i tried to create the JVM by running my application it pops up the message "The application failed to start because jvm.dll was not found. Re-installing the application may fix the problem." I tried out setting all the environment variables to include the jvm.dll(PATH set to c:\j2sdk1.4.2_05\bin;c:\j2sdk1.4.2_05\jre\bin). Still got the same message. Then i re-installed java platform once more. Even now i get the same error. I have more than one jvm.dll at locations jre\bin\client and server, oracle has some jvm.dll . Will that be a problem? if so can i remove those? which of them should be removed and how?
The code i'm using is
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#include <jni.h>
#include <windows.h>
//#pragma comment (lib,"C:\\j2sdk1.4.2_05\\lib\\jvm.lib")
JavaVM jvm; / Pointer to a Java VM */
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JDK1_1InitArgs vm_args; /* JDK 1.1 VM initialization requirements */
int verbose = 1; /* Debugging flag */
FARPROC JNU_FindCreateJavaVM(char *vmlibpath)
HINSTANCE hVM = LoadLibrary("jre\\bin\\server\\jvm.dll");
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void main(int argc, char **argv )
JavaVM jvm = (JavaVM )0;
JNIEnv env = (JNIEnv )0;
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jclass cls;
jmethodID mid;
jint res;
FARPROC pfnCreateVM;
JavaVMOption options[4];
// jint (__stdcall pfnCreateVM)(JavaVM *pvm, void **penv, void *args) = NULL;
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vm_args.nOptions = 4;
vm_args.ignoreUnrecognized = 1;
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if ( verbose )
printf ( "Class: %x" , cls );
/*jvm->DestroyJavaVM( );*/
Could anyone help me solve this problem as early as possible, bcoz i'm in an urge to complete the project.
Thanks in advance.
Usha.

You either have to add to the system path of where is your jvm.dll is located or explicitly link to jvm.dll call GetProcAddress to obtain the address of an exported function in the DLL.

How to call a C function calling a Java Method from another C function ?

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