calling c program from java. hlp please

[sara12345]

hello everyone
I have question
I need to call c program from java
I don't have problem with application or exe file in c it is working but when I call it from java it doesn't work there is no error but it doesn't work because the c program the console must be appeared so that I can enter the input file and then it produces the output file but in java I cann't see the console so please can you tell me the problem
I have used the following code to call c from java:

  String line;
	           String output1 = "";
	          
	                 Process p = Runtime.getRuntime().exec("cpp.exe");
	                 BufferedReader input = new BufferedReader
	                       (new InputStreamReader(p.getInputStream()));
	                 while ((line = input.readLine()) != null) {
	                       output1 += (line + '\n');
	                 }
	                 input.close();

[sara12345]

I have said the console sorry it is not console it must take the input file name from the black screen when I press application file

[collin389]

When you run it, do you see another console pop up, I'm not sure what you are trying to accomplish. Please explain better.

[sara12345]

no I didn't see any console except java console. I'm trying to call whole c program in java. the c program must take input file name in the black screen and must return output file. when I run java using the above code I didn't see any black screen how can I enter the input file name???
can you please tell me what is the problem????
thanks

[collin389]

I think what you are saying is that you run the java from a console and it produces the output of the c program, but you cannot input anything. If that is correct the problem is that you do not get the c programs Output Stream, only the InputStream. What you can do is use a Scanner of system.in on your java program and send that to the c exe via a bufferedWriter of p.getOutputSteam()

[sara12345]

no. the c program must works as follows:
it must take an input file from black screeen and it must return output file.
when I call c program from java I didn't get any thing. the black screen doesn't appear to take input file and also there is no output file I don't know why
although I have run c program from visual c++ it runs fine and also I have run it from command prompt and it works but I don't know what is the problem with java

[Fubarable]

You can hook onto both the C program's (executable program) standard input and output stream from your Java program, just do it in two different threads so one doesn't block the other: Java Programming [Archive] - standard input into a different process

as Collin already has suggested.

[sara12345]

thanks for the reply but it also doesn't work I mean the command line must be appeared so that I can enter the input file name and then it produces output file
but I didn't get any thing
I have write

  Runtime rt = Runtime.getRuntime();
	         Process proc = rt.exec("cp1.exe");
	         OutputStream os = proc.getOutputStream();
	         DataOutputStream dos = new DataOutputStream(os);
	         dos.writeUTF("s");
	         os.close();

can you tell me what is wrong ??

[raqman]

Hi.
Please refer to the url below:
Calling C Code from Java
Regards,
raqman.

[Varun12345]

how can i call a c++ program in java??

anyone have idea?

i tried but have a linking error

[Varun12345]

i hava a java progaram
class HelloWorld {
public native void displayHelloWorld();

static {

System.loadLibrary("hello");
}

public static void main(String[] args) {
System.out.println("\n Hey now calling display method\n");
new HelloWorld().displayHelloWorld();
}
}


also a c program


#include<jni.h>
#include"HelloWorld.h"
#include<stdlib.h>
#include<iostream.h>
#include<conio.h>

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


using as

java helloworld.java

javah -jni helloworld

gcc -I c:\jdk\include -g -c helloworldImp.c -o libhello.so

but this gave many errors in jni.h

how can it be used pls tell me ........
thanks in advance...
;)