call c++ exe from java applet

[jojji]

Hi ,

I am trying to call c++ exe from java applet.For this purpose am using processbuilder.My code is as follows


String line = "";
String s = "C:\\Users\\madsaan\\Documents\\NetBeansProjects\\ CppApplication_2\\dist\\Debug\\Cygwin-Windows\\cppapplication_2.exe";
ProcessBuilder pb = new ProcessBuilder(s);
Process process = pb.start();
InputStream is = process.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
while ((line = br.readLine()) != null) {
JOptionPane.showMessageDialog(Cytoscape.getDesktop (), line);
}


The c++ exe looks like this when started:


1. Find the shortest path from s to t.
2. Find the associating path from s to t within length l.
3. Find the associating path from s to t within (1+beta) times of the shortest distance from s to t.
4. Exit
Please input the command (1-4):

once u input the command ,for example 1 we get

Please input s and t, separated by space:

so how am i supposed to pass arguments line by line .
I tried ProcessBuilder pb = new ProcessBuilder(s,"1","0 1");but all it does is print the following

1. Find the shortest path from s to t.
2. Find the associating path from s to t within length l.
3. Find the associating path from s to t within (1+beta) times of the shortest distance from s to t.
4. Exit

how can i get it to accept all the arguments and give me the final output alone?

Thanks.

[Norm]

how can i get it to accept all the arguments and give me the final output alone?

To communicate with a process, you'd need to use the Streams available from the Process. Read from one and write to the other.
If the program you are executing only gets its data from prompts and reads, then you have to read its prompts and write to its reads.

Or is this an OS piping (> or <) thing where you can "prefeed" the reads by putting the answers in a file that the OS uses to respond to reads.

[jojji]

Hi,

Thanks for your reply.

This is not a OS piping.I managed to get part of it working using input and outputstream
The code is as follows

ProcessBuilder pb = new ProcessBuilder(s);
Process process = pb.start();
final InputStream is = process.getInputStream();
OutputStream out = process.getOutputStream();
PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
pw.println(1);

new Thread(new Runnable() {

public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (java.io.IOException e) {
}
}
}).start();
pw.close();

Right now am able to pass only the first argument.Am not able to pass the second set of arguments when it asks for

Please input s and t, separated by space:

Help!

Thanks

[JosAH]

Just imagine you, innocently clicking a URL link; a HTML page loads with an applet; also just imagine that the ms windows command "format'' were written in C++. Your applet is able to start that program and it formats your entire hard disk. Would you be happy?

kind regards,

Jos

[Norm]

able to pass only the first argument.Am not able to pass the second set of arguments

Are you talking about arguments to the program? Arguments go on the command line following the command name.
Or are you talking about responding to console prompts from the program?

To figure out the logic and calling sequences, can you build a small application and use it to work out the techniques?

You start the program in a Process and read its "prompt to the console" via an input stream
You write a response "to the its input console" via an output stream
Then read the next
and write the next
etc

[jojji]

I tried that as follows

try {

String s = "C:\\Users\\madsaan\\Documents\\NetBeansProjects\\ CppApplication_2\\dist\\Debug\\Cygwin-Windows\\cppapplication_2.exe";
ProcessBuilder pb = new ProcessBuilder(s);
Process process = pb.start();

OutputStream out = process.getOutputStream();
PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
pw.println(1);

OutputStream out1 = process.getOutputStream();
PrintWriter pw1 = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out1)));
pw1.println(1 + " " + 2);


pw1.close();

final InputStream is = process.getInputStream();
new Thread(new Runnable() {

public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (java.io.IOException e) {
}
}
}).start();

} catch (IOException d) {
d.printStackTrace();
}
}
}


it goes into an infinite loop .please help!.

[Norm]

Please use code tags when you post your code to preserve formatting.

it goes into an infinite loop

What does the program printout while in the loop?

[jojji]

am responding to the console prompts

[Norm]

Can you explain your last post?

[jojji]

Hi,i changed the code a little bit.(as follows)

ProcessBuilder pb = new ProcessBuilder(s);
Process process = pb.start();

OutputStream out = process.getOutputStream();
PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
pw.println(1);
pw.close();
OutputStream out1 = process.getOutputStream();
PrintWriter pw1 = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out1)));
pw1.println(1 + " " + 2);
pw1.close();

final InputStream is = process.getInputStream();
new Thread(new Runnable() {

public void run() {
try {
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (java.io.IOException e) {
}
}
}).start();



Now it does not go into an infinite loop but it prints only the following


1. Find the shortest path from s to t.
2. Find the associating path from s to t within length l.
3. Find the associating path from s to t within (1+beta) times of the shortest distance from s to t.
4. Exit
Please input the command (1-4): Please input s and t, separated by space:

So,that means it taking in the first input(pw.println(1)) but after that if i run the program again it prints the same and does not take the next input (pw.println(1 + " " +2)).if it takes the second input then i will get the final output.Thanks for ur help.

[Norm]

Please use code tags when you post your code to preserve formatting.

[Norm]

What happens if you don't pre write the answers?
Read the prompt
Write an answer
Read another prompt
Write another answer
etc

[jojji]

Hi,

Am not pre writing the answers.I read one prompt,print the input,read the second prompt and print the input.it works for the first prompt but not for the second.I have pasted the formatted code as below

               ProcessBuilder pb = new ProcessBuilder(s);
                Process process = pb.start();
               OutputStream out = process.getOutputStream();
                PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
                pw.println(1);
                pw.close();
                OutputStream out1 = process.getOutputStream();
                PrintWriter pw1 = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out1)));
                pw1.println(1 + " " + 2);
                pw1.close();
                

                 final InputStream is = process.getInputStream();
                new Thread(new Runnable() {

                    public void run() {
                        try {
                            BufferedReader br = new BufferedReader(new InputStreamReader(is));
                            String line;
                            while ((line = br.readLine()) != null) {
                                System.out.println(line);
                            }
                        } catch (java.io.IOException e) {
                        }
                    }
                }).start();
                
            } catch (IOException d) {
                d.printStackTrace();
            }
        }
    }
}

[jojji]

sorry.am not sure how to use code tags in this forum.

[Fubarable]

sorry.am not sure how to use code tags in this forum.

The FAQ's or the link in my signature (to the faq's) will show you. You don't have to repost your code but rather should edit your posts above.

[jojji]

great.Thanks

[Norm]

Am not pre writing the answers.

It looks to me that you are writing the answer BEFORE (pre) reading the prompts

  
                pw.println(1);  // prefeed answer 1
                pw.close();
                OutputStream out1 = process.getOutputStream();
                PrintWriter pw1 = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out1)));
                pw1.println(1 + " " + 2);  // prefeed answer 2

[jojji]

I havent clearly understood what outputstream and inputstream exactly do.its very confusing actually.how do u think i should structure the code.please help

[jojji]

Hi,

I changed my code but am still getting the same result as before

ProcessBuilder pb = new ProcessBuilder(s);
                Process process = pb.start();
                
                OutputStream out = process.getOutputStream();
                PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out)));
                

                OutputStream out1 = process.getOutputStream();
               PrintWriter pw1 = new PrintWriter(new BufferedWriter(new OutputStreamWriter(out1)));
               
                

                 final InputStream is = process.getInputStream();
                new Thread(new Runnable() {

                    public void run() {
                        try {
                            BufferedReader br = new BufferedReader(new InputStreamReader(is));
                            String line;
                            while ((line = br.readLine()) != null) {
                                System.out.println(line);
                            }
                        } catch (java.io.IOException e) {
                        }
                    }
                }).start();
                
                  pw.println(1);
                pw.close();

                 pw1.println(1 + " " + 2);
                pw1.close();
                
            } catch (IOException d) {
                d.printStackTrace();
            }
        }
    }
}

[Norm]

What happens if there is only one output stream and it's not closed until all output has been written?