Using external .exe for input stream

**SimJim21** · August 9th, 2021, 12:35 PM

I have an external console app I am trying to read from. My code starts the .exe process. I am using a buffered reader, .getinputstream, and then .readLine. I then print the Line to the console. I have some unexpected results doing this. After starting the Process i do not see it in my task manager processes. I used isAlive() to verify that the process has actually started and, it returns true. If I run the process in a separate java file, the process starts correctly. I can see it in task manager processes.

2)When running the code, I get intermittent results. Most of the time .println(Line) does not print anything(in the eclipse). I have seen the println work on this code a couple of times but, it is not constantly working.

I have only been writing in java for about two weeks, so my understanding of how most of these functions work is remedial. I feel like this is either a timing issue between the .exe and my code or i am using something for the wrong purpose as well as making some things harder than they have to be. Any help would be greatly appreciated.

Windows 10, Eclipse IDE

!EXPECTED RESULTS!
STALL WARNING = 0 // APP SENDS SIGNAL THAT STALL IS OFF
STALL WARNING = 1 // APP SENDS SIGNAL THAT STALL IS ON ECT....
STALL WARNING = 0
STALL WARNING = 1

!ACTUAL RESULTS!
.... //ELAPSED TIME 5-20 MINUTES NO RESULTS
STALL WARNING = 0
.... //ELAPSED TIME - SEEMINGLY RANDOM
STALL WARNING = 1 // RESULT WILL EITHER RETURN 0 OR 1 REGARDLESS OF THE VALUE THE APP SHOULD BE SENDING AT THAT TIME

public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
 
 
 
	try {	
			 String line;
 
			 InputStreamReader Isr = new InputStreamReader(Ignition().getInputStream());
 
			BufferedReader input = new BufferedReader(Isr);
			{
			    while ((line = input.readLine()) != null) {
				  line = input.readLine();
				  System.out.println(line);
				  line = input.readLine();
 
			    	System.out.println(line);
			    }			
 
		         input.close();
		    }
 
		} catch (Exception e) {
			e.printStackTrace();			
		}
 
	Ignition().destroy();
	System.out.println("Program ended");
	 }
 
	public static Process Ignition() throws IOException{
 
 
				 String appname = new String("TaggedData.exe");
				 String Fname = new  String("C:\\Users...\"+ appname);
 
 
 
 
 
		String command[] = {Fname};  
 
		ProcessBuilder Prep =new ProcessBuilder(command);
 
		Process P3d = Prep.start();
 
       return P3d ;
 
	}
 }

**Norm** · August 9th, 2021, 03:58 PM

I get intermittent results.

Can you copy the contents of the console that was printed that shows what you are talking about?
Add some comments in the print out where the results are not what you expect.

In the code I see that three lines are read but only the last two lines are printed.
The first line that is read is not printed.

**SimJim21** · August 10th, 2021, 08:54 AM

Originally Posted by Norm

In the code I see that three lines are read but only the last two lines are printed.
The first line that is read is not printed.

Does this mean that
while ((line = input.readLine()) != null) is already reading the line into the "line" string?

If so, am i possibly writing a 0 length string to "line"?
that may be why i am not seeing my results.

**Norm** · August 10th, 2021, 09:00 AM

while ((line = input.readLine()) != null) is already reading the line into the "line" string?

Yes. The call to readLine returns the next String from input.

why i am not seeing my results.

The line that was read is not printed. Add a print statement immediately after the while to print line.

I would expect the output to be this:
skips line 1
prints line 2
prints line 3
skips line 4
prints line 5
prints lint 6
skips line 7
etc...

**SimJim21** · August 10th, 2021, 12:35 PM

Originally Posted by Norm

Yes. The call to readLine returns the next String from input.

The line that was read is not printed. Add a print statement immediately after the while to print line.

I would expect the output to be this:
skips line 1
prints line 2
prints line 3
skips line 4
prints line 5
prints lint 6
skips line 7
etc...

Norm, You are the MAN!!! that was the problem. it was writing a zero length string over my string var. Instant updates now. As I said Java is very new to me. I didnt know checking the string like that would assign the value as well. Makes sense thought. Thanks a lot for answering such a noob question.

**Helium c2** · November 13th, 2023, 02:20 PM

I know this not part of the problem at hand, but I must ask this question. external .exe input stream file that you are talking about, is this also the same file as the .exe file to be download for the (JRE)? To my understanding, this .exe files allows a user to view other people's picture files for example, over the internet or www. Just that the other person to view the file must also have the (JRE) platform on his or her personal desktop computer. And that you're learning how to make .exe files for others over the internet? To give out. To view picture files or other files. Was this the case in writing this program?

--- Update ---

All I'm going to be straight forward honest on this forum because you guy are smarter than The Garden Island dot com blog. Of which I've been on for 13 years now. It went from a forum to a blog and now uses a blog type website, accepting html from any client who knows html.

I'm trying to see if I too can make a simple .exe class file from Java, and my home network to store the Java class file. Also on the JRE and development kit. This being my home pc. Then storing a file on there to pass it out to customers. Just so they can view the pictures I've attached to their web html pages. URL. I know I came to the right forum and correct topic. Input stream files. This will take time. But I need to write a program in Notepad, then compile it in java. Then store it on the development kit. Finally inform my clients or customers they too can view the pictures on the blog. That's my miniature size project now. Using my home pc as a network for others to view picture files. But first I have to write this class files so they can just view it on my network with out any intermediate issues in networking. ie..extra cost. Or extra work. whatevers. But just so it will be easier on them.

And not need a JRE on their part. Just the .exe file a small one to input it on their computer to view the blog. Using the Java prorgram. So that's where I am at. I don't know yet how to write the .exe program yet, but I'll figure it out.

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