I wrote a java program, which manipulates Word documents (docx) with Apache POI. It runs fine within Eclipse, and it runs fine as a runnable JAR on my computer (Windows 10).
I copied that JAR to another computer, and it is starting up normally. The GUI behaves like expected.
The problem is the Word document I write out (docx).
I am performing two types of changes. The first one is the addition of new paragraphs or concatenation of content to the runs. If I stay with this, the document gets written into the file system correctly. The second type is the simple replacement of content within the runs (changes of words and some grammatical changes). I would see that part as the "simpler" one, but if I stay with this or if I combine both change types, no document is written out at all. It does look like there is a bug, but there isn't one because it worked fine on my system.
I wrote myself a function to write out an error log (txt) to get information about that issue. This one worked on both systems. But the log didn't get any information, why the document was not written out.
I suppose there are some Windows security settings which interfer with my program or something like that. The computer that does not like to run my program has Win 7 installed on it, and there are some security domain settings, which affect all other computers in the local network.
Does anyone experienced something similar yet? Any suggestions what to check? Suggestions how to find out if an error happened are appreciated as well.
OK, the problem got solved by simply updating the Java version. I saw that update icon in the system tray, which didn't open update the update dialog. So I wanted to update the Java-version at least.
When I wanted to de-install the current Java version first, I noticed that the Win7-machine hadn't a Java-update for three years now. It was just installed in 2014. As soon as the recent version was installed, everything worked like expected again.
The strange behavior that some parts of my program worked and some not, confused me. I hoped that the Java update would fix this, but I doubted that. I didn't knew that old versions make programs run unpredictably.
Related
How is the java utility that begins the process of launching a class told to "spill its guts" on what it's doing as it tries to load classes?
In particular, what file paths is it TRYING to access, only to perhaps discover whatever it's looking for is not there, at least as it interprets the specification given? There was a way to get that information, but I can't find it now.
Note that this is Java version "1.8.0_333" on Windows 10.
I've tried every flag known to me, via the -h and -X flags, and I strongly suspect what I'm looking for is (was) an X flag that's been removed, just as the -X help output warns. And so, there must be an OS way to figure this out, I sure hope!
You might ask why? Whatever for? What are you trying to do? Well, that's the bulk of this question's text. To wit:
As one of the very early users of Java (I started with 1.1) way back in the '90s, I had an issue moving an application suite I'd written for my company on Linux to MS Windows and I got it working by using Cygwin. Along the way, this same sort of issue came up and I quite vividly recall having found a mechanism for getting the Java launcher to articulate just what file specifications - paths - it was actually using in searching for the appropriate class. And through using this, I found that the CLASSPATH was being specified incorrectly, and with some experimentation, I got it working reliably. Now I need to do that again!
This flag I'd used was immensely helpful in figuring out just what the file specification format CLASSPATH needed to be (we're not talking semicolons here) this combination of OS, Java, and Cygwin. After some hours of what I hope was reasonable hunting, I'm wondering if this capability has been removed at some point? Either that or "I'm looking for the wrong thing." Heck, since the source is available (I think!), maybe some brave soul has hacked the java utility to do such a thing?
It may help to understand that for this application I wrote for my company, it was a major goal to have the source work pretty much the same on all Windows and Linux / Unix systems (and at the time, macOS), and just use a configuration file to tell the code what's different. And that wasn't easy to figure out, but with this flag, it wasn't that hard, either.
But, unfortunately, I haven't needed this knowledge since I figured it all out all those years ago, and apparently, this little kernel of knowledge is very hard to find today. Or, it's no longer pertinent to the modern version(s).
I don't think this has anything much to do with the actual problem, but it may help in people's thinking if they understood the scenario: The current situation is that I have a fully functional installation of this software on Windows 7 to use as a comparison for how to configure things on Windows 10 (and hopefully younger). The Windows 7 is running a pretty modern Cygwin installation and very nearly the most modern Java - just a sub-version away from the new installation from last week on a Windows 10 box. (Everything's bright and shiny new on the new box.)
The required format for CLASSPATH on the nearly identical but fully functional Windows 7 system is:
CLASSPATH="C:/opt/OurInstallationDir/lib"
And that's it.
This value is picked up in several places as the code later needs to launch Java itself to do some unusual things. However, the java command that gets it all going is launched from a C program - not that that matters for this problem - but the C program (compiled under Cygwin, but perfectly runnable from any Windows environment) helps ensure that the Java environment is secured (policy file contents and so forth) before getting into Java, else it refuses. And this program on Windows 11 launches Java just fine, it's just giving it a CLASSPATH that isn't useful, apparently, even though the files are there where they should be, etc.
Configuring things as before just doesn't work, even from the command line. No version of specifying CLASSPATH seems to work if it's more than a dot; the only thing that works, is being in the /lib directory when starting and using "-cp ." ... But that's just not going to fly for so many reasons! To be a little more clear, I've tried reversing the slashes, using /cygdrive/c/, and whatever else I could think of. But, at least we know that if you're in the directory and use -cp, it will find and launch the program. So, there's nothing wrong with the Java, just pointing the java utility at it.
Again: How is the java utility that begins the process of launching a class told to "spill its guts" on what it's doing as it's trying to load classes?
You use this construct on the JVM:
java -XX:+TraceClassPaths -cp "C:\opt\SomeDirectory\lib" myClass
I was able to get confirmation of what Java was using, not only for my CLASSPATH, but "internally" by using the above.
The fact that it echoed back both what I was doing and what it was doing somehow gave me the insight to check everything about it. Java itself doesn't work (at all) if it's installed in a location that it thinks has a link in it, and it's own fetches go right back to the system disk specification.
From that I found that Java on Windows won't take a CLASSPATH that has a link in it!
Simply ensuring that the whole tree was specified "from the top" of the drive it's on works. If it's not, it won't.
It's now working happily using the syntax noted above.
This is quite different from every other application I've seen on Windows. But, well, it's Java!
This really came from a pointer from Mark Rotteveel who commented above about this article: How to track when class is loaded and destroyed in jvm? And therein I learned how to get the list of all the options the presently in-use JVM supports. All Java developers should be aware of this in my opinion, so thanks to Mark for that.
For quite some time I have encountered this issue that when doubleclicking a runnable .jar file it won't execute. Today I thought I'd have a look into solving this issue and read a bit through various SO articles regarding this topic.
First of all I have to say the following:
The problem occurs on my company's notebook running WIN 8 as well as on
my private WIN 10 desktop
I'm pretty sure about 1.5 - 2 years ago on the laptop doubleclicking worked
On the desktop however even directly after installation (which was in October last year) doubleclicking didn't work and it might be that I even already tried fixing the issue by reinstalling the JRE
As opposed to many situations described in various posts I can properly run the applications by calling "java -jar application.jar" in cmd but doubleclicking AS WELL AS trying to "open with" Java SE platform binary results in nothing happening
As suggested by several posts I tried running Jarfix however now the behaviour is as follows:
I had written a client-server application for my bachelor thesis which worked perfectly fine, I actually ran the application yesterday through cmd. After using Jarfix I'm now able to start the server by doubleclicking whereas the client side won't do anything when doubleclicked. I already checked for the correct filetype association as described in this post and everything looks correct.
Also I of course checked this with different programs as well and not only with my own applications. The same issue also appears for example (on my WIN 10 desktop) when trying to run Life in the Woods (for those not knowing it, it's a quite popular Minecraft mod pack) whereas it worked perfectly fine on my previous WIN 10 desktop when doubleclicking.
The problem that I have with this issue is not that I'd not be able to bypass it by running cmd commands but on the one hand it's simply annoying to always cd to the desired location and run this command and on the other hand it's simply something that has to definitely work after installing a JRE. It doesn't make any sense that for most people it works and for some few people random stuff happens - all more or less under the same conditions, that's not how any kind of software should behave.
I'd be really happy if anyone could help me solving this or point me towards anything I might have overlooked and forgot to check.
EDIT:
As pointed out by #VGR file operations using relative paths might be the reason for the problem hence below the two cases where file operations are being used:
Server-side:
File file = new File("C:/Util/authHashes.lvs");
Client-side:
systemProperties.put("javax.net.ssl.keyStore", "C:/Util/auth/labkey.jks");
systemProperties.put("javax.net.ssl.keyStorePassword", "password");
systemProperties.put("javax.net.ssl.trustStore", "C:/Util/auth/labtrust.jks");
What is weird is that both classes use absolute paths but the server starts when doubleclicking while the client does not. If both use the same kind of path shouldn't they both behave exactly the same?
Foreword
I've seen some questions related to this in other languages and done quite some research on this. First, before we begin going down the rabbit hole, I must describe why I'm doing this. I'm pretty printing a binary tree and I found a way to do it that I don't think anyone else has found (can't find it anywhere on the web I've searched forever). It solves a lot of the problems related to spacing and conflicts and I'll probably provide it as an answer to prettyprint Btree questions later. Anyways, an essential part of doing the above is to be able to move the line feed (the cursor) one line up. I will also settle for moving the carriage return one line up.
I have made three EDITs to this question named "Edit 1-3" near the bottom.
My specific Windows version (might be relevant): Windows 10 v1607
OS build: 14393.2035
The problem??
The problem is that this is easily done with ANSI escape characters
ANSI escape codes: https://en.wikipedia.org/wiki/ANSI_escape_code
With "\033[A" being the specific code I want to implement (got it from a question about moving one line up in python).
The problem
So problem solved right? Oh no, not even close. The problem is, apparently windows had this """wonderful""" update that may have broke everything ANSI/console related. The below links to a question about this but with different ANSI requirements however the root problem is the same.
How to print color in console using System.out.println?
tl:dr It doesn't work for windows for some reason, you need a big library to do this or something else.
Sooo then I tried doing some in-depth research on the update itself and why this happens to be windows specific (of course) and I was led to this.
the root cause of windows problem: https://github.com/Microsoft/WSL/issues/1173
tl;dr:
Basically, the update changed a default setting for cmd.exe which is the default console that java uses. What changed was how the console setting for ANSI codes are processed for 'child applications' AKA java (stuff that uses the console but isn't console itself). The default Before the update was that child applications inherited the default of console which was to have ANSI enabled. NOW (because apparently, the previous default broke things) they changed it so that child applications DO NOT inherit the default settings from the console. This means java has to effectively set this console mode itself if java wants to have ANSI enabled. There are obviously a plethora of libraries for the java command to do that but of the good available ones, there are some issues. Firstly they require maven and I don't want maven, also I don't like NEEDING a million extra libraries to do something very simple and it adds to the number of things my code relies on (which is bad). So I'm trying to avoid simple solutions like "just use JANSI" to setConsoleMode for ANSI.
What I've tried after this
after I was done reading/understanding that I tried going into my Registry Editor and trying to change the default setting of the console (cmd.exe) to always enable ANSI even for child applications (AKA java). It had been suggested in the GitHub discussion but to my surprise the specific setting wasn't even there for me. (it was supposed to be in Computer -> HKEY_CUURENT_USER -> Console between "TrimLeadingZeros" and "WindowAlpha").
Try 2
Since I couldn't edit the console setting without big libraries full of things I don't want, I tried thinking outside the box and I messed around in java settings. I discovered where exactly java sets it's console and discovered that I could change that setting to use a different console in java. I had recently installed git and known that git bash was available so I tried that using the below question (and google in general) as a starting point.
https://superuser.com/questions/1196463/start-sh-exe-bash-with-given-path
Third time is the charm?
I couldn't get the darn thing to work. It didn't return any errors or do anything new, like at all. It was even set 'for the current project' so it should've done something different when I ran my project no? I believe part of the problem is that my root git folder is screwy (not in program files). This is probably because the computer I'm using is a work computer and maybe some setting there affects where git was installed, I don't know but what I do know is that when I changed consoles I tried this path:
C:\Users\abbotts1\AppData\Local\Programs\Git\bin\bash.exe
I also tried:
C:\Users\abbotts1\AppData\Local\Programs\Git\bash.exe
and
C:\Users\abbotts1\AppData\Local\Programs\Git\bin\sh.exe
and
"C:\Users\abbotts1\AppData\Local\Programs\Git\bin\sh.exe" --login -i
And after each change of console I tried this code:
public class ExpressionEvaluator {
public static void main(String[] args) {
System.out.println("1");
System.out.println("\033[A");
System.out.println("2");
}
}
And I always got:
1
Extra Line here
2
As the output. If I removed the 'move cursor up' ANSI println statement attempt I got:
1
2
What I wanted was:
2
1
(the whole point being, I'm able to move up a line freely)
I've also tried making them print statements and that didn't work either.
So I'm now at wits end
So here is what I want, an answer something like:
A nonintrusive way to change the setting for cmd.exe to allow child applications like java to use ANSI BY DEFAULT when ran
OR a nonintrusive library that doesn't require maven and a million other things to enable ANSI so I can run the ANSI in java in the console and get my desired output
OR a programmatic workaround that allows me to effectively print one line up without this whole ANSI thing
OR help to configure IntelliJ console so that I can actually use a different console and use ANSI to print one line up
To address the obvious concerns
Since 1 and 4 are superuser questions and 2 is 'I need a library' and offtopic I'm more talking about point 3 here. If there is no workaround for this and the answer is one of the offtopic ones just tell me there is no workaround. I don't know how else to ask this question since it is a 'programming specific problem' it just has many solutions some of which are not 'on the topic' because they aren't programming solutions. If the only answer is 'the solution isn't on topic here' then I'll go ask in the appropriate place. Let me know if I should delete this question when I go to ask it somewhere else.
What I think might work for on topic part of this
Since 3 is on topic here I'll discuss what I'm thinking:
Maybe I could make some sort of system to print only to certain arrays instead of moving up and down lines (i.e. have an array to represent the lines, traverse the tree and instead of moving up and down lines, just switching the array to print to). I don't see this as very efficient and Its kind of a waste of arrays and processing power but if its a solution I'm willing to hear it. That's all I can 'think of' but most of what I've tried is trying to get ANSI to work.
For future reference:
what is the appropriate way to ask these questions with multiple off-topic solutions/ solution questions? Is it better just not to ask them at all? Do solutions that involve questions constitute a chameleon question? I don't feel like bringing the meta effect upon myself.
Edit 1: where I'm at so far:
I've tried the whole git bash thing again and boy was it a process. The actual git bash path in the terminal needs to be in quotes with the --login -I arguments coming afterward. Ex:
C:\Git\bin\sh.exe --login -i
This setting is for the java terminal. THEN you have to set a windows environment variable named PATH to your java JDK. Go to your path environment variables (there are a million and one youtube videos for that) and set a new variable named PATH to your JDK. Ex:
C:\Program Files\Java\jdk-10.0.1\bin
This question:
How can i make gitbash find the javac command?
Goes through that process extensively
Tl;dr You have to set a windows path variable this in order for git bash to recognize the javac and java commands.
Once that's done you need to actually run your java and javac commands like you would in any terminal. BTW be careful because paths in git bash require a two '\' notation instead of the normal '\' so your source directory path might look like this:
C:\IdeaProjects\Calculator\src\
Then you just run:
javac ClassName.java
java ClassName
BUT THEN it doesn't actually print the ANSI output, it prints the raw escape characters. Also, I found out I was using the WRONG escape sequence (I had the wrong number to represent the 'esc' button since the 'esc' key is represented as some number, but I had the wrong hex number I was using like x330 or something). I also learned that the notation is like this:
'esc key hex number' + '[' + 'parameter hex values separated by commas'
so this might look like:
\x1B [ A
where the actual letters and numbers are hex value stuff (without the obvious 0x...) and the first escape hex value has an x in it (why?). Anyways, when running them in Java as strings you need to escape the escape character (duh right?) with an extra '\' so, for example, the code might look like:
System.out.println("\\\x1B [A");
I just noticed that stack overflow escapes these too so I
actually have three '\' but for you guys, it only displays two '\',
weird right? Anyways back to what I was saying
BUT STILL, the output doesn't actually work! This is where I'm at. I've done the above and I 99.9% know git bash is installed right and runs fine but when I run this:
public class ExpressionEvaluator {
public static void main(String[] args) {
System.out.println("1");
System.out.println("\\x1B [A");
System.out.println("2");
}
}
I get this in java console (not git bash??):
1
\x1B [A
2
and this in git bash:
1
\x1B [A
2
What I actually want is:
2
1
Because the ANSI escape character is supposed to move my cursor/linefeed/whatever, one line upwards. The same thing happens if I run the above code but instead use the ANSI code: "\x1B [F". Only raw ANSI is output. I'm pretty sure git bash was supposed to be 'natively ANSI aware' and I've seen people say that on websites so I don't know why it isn't working.
And I still don't know for sure if those are two separate console outputs or the same console output. I really can't tell so if anyone wants to leave a comment saying 'yeah its the same dummy', I'd appreciate it because I can't find a definitive source out on the web that it is. I think it is but nothing other than the console setting in IntelliJ indicates that as true.
I've heard rumors of a TERM variable that needs to be set or otherwise manipulated on windows. I've checked myself what it is using:
echo $TERM
in git bash and I got back:
cygwin
So I don't exactly know if that's good or bad because I've literally gone through all the search terms you can think of and they all lead to the same basic page of results for 'git bash colors not working' and most of them involve windows 7 (don't have it) installing maven/jansi (don't want or shouldn't need it) or some other language that isn't Java and using some other IDE which isn't IntelliJ. Some pages that do have my specific requirements have said something about TERM supposed to be xterm or some other thing like xterm-256 or something for 'color' output, something like this. I am so unfamiliar with this stuff so I don't even know where to begin.
Too long give us a tl;dr
I need to know why git bash is printing raw ANSI instead of actually using the ANSI.
what I know
I'm using git bash with IntelliJ, 99.9% sure I have my path set correctly, I am able to run my java class from git bash, I have it set as the IntelliJ terminal and I currently have the windows TERM variable set to cygwin.
What I don't know
I don't know what TERM needs to be and can't find it on the web, I can't tell if the IntelliJ console that appears when I click the green arrow 'run' is the same as the git bash console, and I can't figure out if some other thing is preventing me from actually interpreting the ANSI.
What I need
I need a simple explanation, something straight out of r/ELI5 of what is wrong with git bash if anything and how to fix it. If it can't be explained simply or nothing is wrong then maybe I'll try another supposedly 'natively ANSI aware' terminal. I think Powershell was another option that was listed. My best bet is that the TERM variable needs to be something else, or git bash was never really natively ANSI aware and capable, to begin with. I've seen other questions with the same problem for colors but their fixes are for older versions/different languages and things or they don't actually work. I have yet to find a good page for 'git bash outputs raw ANSI in IntelliJ' and I've used variations of those exact words for hours now. All I can get is long GitHub discussions on the 'bugs' related to this and they confuse me, don't lead to solutions, and may be active or just don't contain any resolution.
Edit 2
After doing some more research I've learned that my previous escape code was correct:
\033[A
\x1B[A
should be similar.
I also learned that it isn't the console I'm using that's the problem, its Windows itself. I now know this because I've tried compiling and running on cmd.exe , git bash and powershell. To change the default setting talked about earlier (consoles not supporting ansi for child applications) you have to EXPLICITLY enable it via the program itself rather than rely on a console or something.
link to a question that explains this in Python here:
How to use the new support for ANSI escape sequences in the Windows 10 console?
tl;dr
The method that they use is something called getConsoleMode and setConsoleMode and VIRTUALTERMINALPROCESSING flags. Apparently you need to use these to actually set the console mode to support ANSI. I don't currently know if those are things that are in java hidden somewhere or (likely) something that needs to be added to the base java libraries. I'm going to try and figure out how they actually get the ctypes thing from that question (seems to be what they're importing to sue these methods) and get the methods I need. Once I do I'll post that as an answer unless one of you figures it out before I do and can explain it better.
Apparently, the escape sequences work fine if you only use them from the console but If you use a "child application" then they don't work. So at the very least we now for sure know the root cause of the problem.
Edit 3
Found this which is highly relevant especially the console virtual terminal sequences section (lefthand navbar):
https://learn.microsoft.com/en-us/windows/console/console-virtual-terminal-sequences
This which, near the bottom has a whole C-implementation of how to enable the console to read ANSI. Apparently, this doesn't need libraries at all but the process to actually change the console defaults to use code like this requires sysadmin privileges, intimate knowledge of the program files and a whole host of other things (at least if you're before the windows 10 update when color support was changed). Now it's still disabled by default but can be enabled. I don't yet know how to try ANSI from the console directly. I've tried multiple
echo \x1B[(insert ANSI code here)
but none of the commands seem to work in ANY terminal (cmd, git bash, powershell). They just return the raw code
\x1B[(whatever the ANSI code was)
I obviously am new to the console so I might be using the wrong command, if so feel free to enlighten me but the examples I've seen use echo. ANYWAYS, I thought that calling the ANSI directly from terminal was supposed to work since its supposedly enabled by default just not child applications (post windows 10 update) BUT maybe its not, maybe its disabled by default and even when enabled its still disabled for child applications (Java) unless explicitly changed in said child application (java). I'm going to try to see if it's possible to enable ANSI directly from the console, or if the linked C-code needs to be directly ported to Java or ran in the console just to work. The problem is I don't know how to get the imports/includes that the C-code uses and use it for code in java. I'd rather not just accept a coded 'solution' in C and try and use that alongside java code, I'd rather translate, understand it better and have my own code that does the same thing.
Another option I've been told is something called ANSICON which is like some sort of plugin that you install in the console with the -i flag and that's supposed to enable ANSI at least in-console. I found this
https://community.liferay.com/blogs/-/blogs/enable-ansi-colors-in-windows-command-prompt
the above explains that process in a little more detail.
My specific windows version and the version of the update
Another thing I learned was that the specific version of windows 10 that the 'update' that changed ANSI console behavior was like windows 10 v1151 or something, I'll try and find the webpage to source this directly but I currently have windows 10 v1607 so I think I should be good. Included in that was the actual OS build which I have 14393.2035 and I think that was identified as a particularly intermediate update to this process in one of my previous links (I believe its the one with the whole GitHub discussion about the update, you can find it here: https://github.com/Microsoft/WSL/issues/1173). I have a work computer so I can't really make system updates because I'm not an administrator and I doubt IT would let an intern go around updating work computers.
Anyways, I'll continue on trying to see if I can get the C-code to java, I'll test it and then try and post an answer. If ya'll are ahead of me let me know.
The python way you reference in "Edit 2" (https://stackoverflow.com/a/36760881/309816) simply invokes Windows-specific native code (kernel32, which is non-portable) to "fix" this.
I suppose you are OK with that and want to do the same in Java (i.e. invoke kernel32 when you detect Windows)...
A very lightweight library for achieving the same in Java is JNA which has out-of-the-box wrapper for kernel32 (see: https://java-native-access.github.io/jna/4.2.1/com/sun/jna/platform/win32/Kernel32.html)
You seem to be after this method: https://java-native-access.github.io/jna/4.2.1/com/sun/jna/platform/win32/Wincon.html#SetConsoleMode-com.sun.jna.platform.win32.WinNT.HANDLE-int-
Hope this works for you.
EDIT: technically, you only need jna.jar (see getting started here: https://github.com/java-native-access/jna/blob/master/www/GettingStarted.md), but I would suggest you also use jna-platform.jar so that you don't need write the code that generates the mappings for kernel32 at runtime yourself.
Home for JNA: https://github.com/java-native-access/jna
I think adding 1 (or 2 if you add jna-platform) jars that have a very specific scope (doing native calls without all the JNI preparation overhead) is lightweight enough. You don't need to generate any headers, or change anything in your compilation process. It will just work by adding those jars to your classpath.
You should also clarify in your question that this is about Windows. Maybe edit the title to: "Printing up a line in java console (reverse of '\n') on Windows" as this is really about a platform-specific concern that you want to address with Java.
I just wonder something about java applet with awt. I quite disappointed with this problem and want to throw it away sometimes. Below are my descriptions:
I already created one application using java applet with awt controls on my own computer, let's say computerA using Window 7 32bit Operating System. To up and running this application, I update java version to the latest one.
Application is working fine with computerA. However, this application also need to run on the others as well. As my own situation, I run with another computer, let's say computerB using Window 7 64bits Operation System. I knew that the application created with 32bits java version, thus I decided to install this java version on computerB. However, when I run the application it can only display interface on browswer, but some of its function did not work.
Yet I didn't throw it away, I decided to configure in the last computer, let's say computerC. This computer use Window 8 32bits Operating System. I did configure as I did with computerA and computerB. The result is still exact as computerB.
I also checked up this solution on here, but it is not fit my problem.
Here are my questions:
What is the exact problem on here?
Where does the problem come from?
Is it solvable?
How can I solve this kind of problem? Any helps?
Update:
PostgreSQL Database also install in other local computers as well.
I noticed that If I convert my code into eclipse project, it worked fine. No problem at all.
Thanks in Advance.
I'm having a problem that, at this moment, I don't even know how to investigate properly. Any recommendations on how I can get more information are welcome and appreciated.
My company sells a product with a WinXP PC at its core. One of the product's tasks is being able to start a video player on demand -- VLC, in this case. (To be specific, VLC 0.8.6d; it's several years out of date, but upgrading is problematic for a few reasons.) The application responsible for starting the player and performing many, many other tasks is written in Java.
I have a test rig sitting next to my desk. It used to work just fine. But for some reason, it now gives a "Send Error Report" window when the Java app tries to start VLC: "VLC media player has encountered a problem and needs to close...." You know the one.
Clearly, I've done something that buggered things up. Problem is, I know neither what it could be nor how I would go about fixing it.
Stuff I know:
It's not a code bug. I run the same software on my development desktop machine, and it doesn't have this issue.
It's not the VLC install, nor is it a malformed video file. When I capture the command used to start it from Java and manually enter that command from a "cmd" window, it works fine.
It's not that sneaky bastich bug where Java punishes you if you don't manually drain STDERR and STDOUT when making a system call. I've got that covered.
I'm not getting any error messages or output when it fails; it just fails and gives me that pop-up window.
I'm stumped. Recommendations for either what it could be or how I can figure out what it is are very welcome.
Well, I’m not familiar with java and VLC, but I would do the following things:
Check that you have identical java virtual machines in both of your desktops. Just in case…
Check the process’s environment variables. They depend on parent process. Maybe VLC uses some of them.
Try to debug crashing with native debugger like WinDbg. Perhaps the call stack will give you more ideas.
Good luck!
My suggestions:
Create a simple java app that just launches VLC
Use your app to launch a simple command line windows program
Use your app to launch a complex program
Check to see if there is a memory constraint issue. Is VLC getting too little memory to run?
This really sounds like a memory/environment issue.
A number of things I would try
Make Sure both test and development machines are identical in every respect, the operating syste(if possible installed from same OS Disk), same JVM version, same memory allocation to JVM (you know those -X-ms stuffs). My fear is not with Java/JVM per se, it is with windows.
Make sure you can lunch for example Notepad from a Java app, and then something like Windows Media Player or MS Word.
Try and launch other versions of VLC to see if it is a VLC version problem.
Finally try and wipe the test box and re-install it(with Windows, you can never tell, a fresh installation might just do it!!)