Develop Reference

In Java how do you debug exe created by JPackage

I am trying to convert an Windows installation of Java app created with Izpack to use JPackage provided In Java 14. The installer builds and installs, but when I try and run the exe it creates it fails, but gives no information about why it fails.
Is there a log or some way of finding out why it actually fails to start ?

Use jpackage --win-console flag to enable console output, and run your app from CMD.exe so can see any output it writes.
However if you leave jpackage --win-console enabled, console output is ON for every other EXE you add with --add-launcher UNLESS the properties file for the launcher contains the line win-console which turns off console. It doesn't seem to work the other way around.
Its easier to work out what jpackage is doing by making the --main-class a Hello World / dump System properties + env.

How can I bring up a console alongside my LibGDX desktop application?

I would like to see some of the System.out and accept some inputs from it for testing my application on other computers which do not have Eclipse on them.

Normally, if you run the jar by double-clicking then the console output won't be shown.
However, you can launch the command line application (Terminal/CMD depending on your OS) then use the cd command to navigate to the directory of the jar file. Then type:
java -jar [app_name.jar]
This will run the application and show output within the console.

Output of application based on Eclipse on Windows command line only visible when piped (not directly in cmd)

We have a Java application based on Eclipse (main class implements IApplication) that is started from the Windows command line. Its output on System.out is not visible/printed into the command window from which it is started. Nevertheless, when piping the output to more, the output is fine. How come?
For example, consider helloworld.exe. When running C:\>helloworld.exe in a command window, the application simply returns. But when running C:\>helloworld.exe | more, the screen shows
C:>helloworld.exe | more
hello world
C:>
On linux, the output is fine. How to see the output on Windows, too?
Some reqested information:
The application is quite large. And I probably cannot cut it down. The output are simple calls to System.out.prinln("xxx");
Java version 1.8.0_60, Eclipse 3.6.2
Using >std.txt 2>err.txt shows that output is indeed on stdout.
Line endings are CR/LF
the .ini file is as follows
--launcher.suppressErrors
-vmargs
-Xms256m
-Xmx4096m
-Djava.naming.factory.initial=com.sun.jndi.fscontext.RefFSContextFactory
-Djava.library.path=plugins
Maybe this issue is related?

If your application is somehow started via eclipse.exe (has no console attached to it) change the call to use the eclipsec.exe (has a console attached to it, note the c in the application name).

You can launch Eclipse RCP based applications using equinox launcher as shown below:
java -jar plugins/org.eclipse.equinox.launcher_1.1.1.R36x_v20101122_1400.jar
Of course you have to find the correct version of equinox launcher you are using in your RCP Application.
This way you would see the console logs.
You can read more about it here: http://wiki.eclipse.org/index.php/Starting_Eclipse_Commandline_With_Equinox_Launcher
EDIT: The reason you don't get console logs when eclipse.exe based launcher is used is because eclipse.exe on Windows spawns a separate process which brings up another command prompt window.

You'd better use a framework to handle your logs like logback
This is much more portable and maintainable.

In your example it seems that you have created an exe from your java code. My guess is that the packager you used to create the exe made some changes to the output target because it is a wrapper for your java program.
Try creating a jar instead and try executing it by java -jar helloworld.jar.

Is the string going to stderr in place of stdout? (or the other way around depending on your expected behaviour).
https://support.microsoft.com/en-us/kb/110930

Java - System.out.println() viewable from application?

I have a Java application that runs great :) While uploading files, it uses the standard output to show progress : "System.out.println(...);".
When I run it in Eclipse, well it works perfectly, but when I run the JAR file, I don't see any console/terminal showing up and printing what I print through "System.out.println(...),".
How can I open a new terminal when my application is launched (it is a Swing application)?
Basically I want to be able to run the Swing application and show information on the side in a terminal / console. Why? Don't worry about why I want to do this ;)
Thanks a lot!
Regards.

Open terminal and run application as java -cp yourjar.jar YouMain or java -jar yourjar.jar if you jar is runnable.
I believe that you do not see output because you are running your application using javaw - the special windows-only variation of JVM that does not have STDOUT at all. If you want to click your application and see output map *.jar file to be opened using java instead of javaw. Alternatively write bat file that runs your application. In this case you will see console.

Use java instead of javaw to launch your application. Double-clicking on a jar executes it with javaw. Instead, open a command line window and type
java -jar thePathOfTheJarFile.jar
If you want to have something double-clickable, then write a shell script containing this command, and double-click the shell script instead of the jar.

Java programme works perfectly in NetBeans, but exits unexpectedly when trying to run

I've run into a weird problem today. I'll try to describe the steps I'm making as detailed as possible.
I've created a Java application in NetBeans. The application runs without exceptions when running within NetBeans by clicking Run Main Project. The total duration of a complete run is about 1min.
When building the project I see the following option in the output window of NetBeans:
To run this application from the command line without Ant, try:
java -jar "C:\java_libraries\PrxJobCommunicator\dist\PrxJobCommunicator.jar"
So i open the command prompt (Windows 7), enter this command + supply a mandatory integer argument and press enter
The application starts running, runs for a couple of seconds and exits without any message whatsoever.
the application writes to a text file at different points in the code, so I'm able to trace the output up to the point when it stops running. I've deliberately put some extra calls to the file writer method in order to find where the programme continues/exits but to no avail. Seemingly the programme simply stops running on a certain line and that's it.
I really don't know what the problem can be: the application runs fine in NetBeans and fails without any message whatsoever when starting from the command line.
Shall I check anything special in NetBeans? Do you know of any special technique to debug a jar file if it's started from the command line?
Any clues are welcome.
Thanks, Andras

I suspect that there is a difference in the classpath when the app is run from NetBeans, and when it is run from the command line.
There must be some kind of exception that is being thrown, have you got an outermost
catch (Exception ) block in the main method?
You could try to debug the application using "remote debugging", although you won't be debugging over a network, you can still use this method to catch the breakpoint started at the command line in NetBeans.
Here's an article that explains how to do remote debugging with NetBeans http://manikandanmv.wordpress.com/2009/09/24/debugging-java-applications-with-netbeans/

Netbeans by default uses your project folder as the working folder. It means when you run your program from console you have to CD C:\java_libraries\PrxJobCommunicator
then run java -jar "C:\java_libraries\PrxJobCommunicator\dist\PrxJobCommunicator.jar"
If above fails check the java version used in your command prompt. java -version
It has to be same as the one used by netbeans.
Finally the library path. Are all the dependent jars placed in the dist folder?