Sometimes when I try to Run or Debug program several times in a row without changes Ecipse does nothing but outputs current Java version in console. Sometimes it works OK and I didn't find any correlation between my actions and its behavior. Any insignificant change in text helps, so this error is not serious but rather irritating. But anyway, do you have any idea why it happens?
Eclipse Kepler. Problem stays both for Java programs and C++ ones (via CDT).
Related
I'm running Eclipse Luna, 4.4.2. Recently I've run some updates (Help / Check for updates) and since then everything is messed up. I.e. my templates are lost and some default which I can't even delete are added ?!? Even worst, when I'm writing to console with:
System.out.println("Some text");
output is not visible in console?!? Like there are many different consoles there: Android, Robo VM, DDMS, Java Stack Trace... but none of them is getting my output?!?
I'm really surprised that Eclipse could get update so destructible. What console should I use now, and why is printing to console not working any more?
"Debugception!"
You may notice that within the first 15 seconds of this YouTube video (from 1:01:01 to 1:01:16), Markus Persson (aka "Notch", creator of Minecraft) has somehow managed to save/update an application and attach a debugger to it while it was already under the process of being debugged, supposedly all with a simple keyboard shortcut. The previously coded application somehow magically became the newly edited one, and seemingly without relaunching it or spawning a new process... It's possible that this is just some form of locally remote debugging, but something about it just doesn't seem quite right.
I've spent several days Googling and asking around on how he was able to do this, yet to no avail. I've found no such option under Eclipse preferences, and whenever I try to save & debug an already running application, it simply launches a separate instance of the newly updated application, side-by-side with the older, outdated one.
Am I missing something? How was this possible?
How was he able to utilize such an astounding, powerful debugging feature?
Thanks in advance!
Update
Okay, so this appears to be a standard feature specific to Eclipse.
Coming from a background in NetBeans and Visual Studio, I'm astounded that this doesn't seem to exist elsewhere (or at least in NetBeans!)...
This is a built-in feature of Eclipse. If you edit a method while the program is running in debug mode, it will compile the new method, and replace the old method with the new version. If some thread was already running that method, it will jump back to the beginning (AFAIK; this might only happen when the program is paused).
You don't need to re-launch the program or set any special preferences. Just edit and save, and the magic will happen.
Eclipse can't always figure out how to merge your changes into the running program - usually if you changed anything outside a method body (including the method's parameters or return type). In this case, you will get a warning dialog, with the option to stop the program, restart the program or ignore the changes.
Sorry in advance. This is a really vague question because I have no idea whatsoever what is going on. I have a Java Swing GUI desktop app that I wrote in NetBeans. While inside of NetBeans, the app works fine and passes all of the tests that I have thrown at it. I've been developing this app over the past several months, deploying it at various phases of its development.
Yesterday, I finished adding and testing some new functionality. I built the application and put it on another computer. I then went to run the program (outside of NetBeans) straight from the jar file. While in the new areas (JDialog boxes), the program crashes. Since I am not in an IDE, I have no feedback to see what is wrong.
The only thing that I can think of (and this is lame) is that I added some switch statements that switch on strings, which I know to new to 1.7. I was previously developing in 1.6. Otherwise, I can think of no reason that the program should work flawlessly inside the IDE, but crash outside of it.
Can anyone offer any suggestions for how I should approach this? I'm at a complete loss.
Thanks very much.
The next debugging step for you is reducing the size of your program until it doesn't crash, then seeing what change you made worked. That should either make the answer obvious or give you a good question to post on SO.
Your idea that it might have to do with switch statements tells you to try:
removing them
removing and compiling on JDK 6 and see if it works
Those are reasonable ways to reduce your program size to see if you can make it run.
I would start from collecting a crash dump data.
If you run the UI on windows you could use DrWatson
If you run the UI in Linux , By default the heap dump is created in a file called java_pidpid.hprof in the working directory of the VM. unless you specify the path yourself by adding this -XX:HeapDumpPath= option to your UI java options.
I'm using Eclipse Juno to debug a java class while testing with junit, but the debugger has been acting flakey. I will reach the breakpoint I want and all seems well with the variable values, but in my console, all of the print statements I set up later in the code are popping out as if I were stepping through it!
(note: they aren't printing as fast as they normally would if I had simply run it, and the output itself is a bit garbled compared to normal output).
Somehow, the code is executing through without me pressing a button. If I try to step through, my view of the code and variables is correct, but debugging stops once Eclipse thinks the program has finished.
Something I should probably mention is that I recently put Fedora on my laptop, so I haven't been running eclipse on it for very long and this is my first time trying junit. Is is possible that I need to download something for my debugger?
I'm new to Java (come from C++/.NET background) and am experiencing very strange error. I am developing w/ Eclipse IDE on Windows XP on my local desktop. It seems that for some reason, an older (and of course buggier) instance of my application stays running for some very odd reason which I cannot understand.
Even when I close eclipse, this old version of my application is running in the background. So unless I reboot, when I try to test new version of the code, this 'old, rogue instance' is fighting for the resources that are used (files on a share) with the newer (hopfully less buggy) version of the code.
Has anyone experienced this? Does the JVM cache old versions of your Java application for some reason? What am I missing here? When I reboot my machine, the instance finally dies...
I was ripping my hair out trying to figure out why the new version of my code still had the same old bug until I realized this was happening... shrug
Thanks for any help!
Do you by chance either run your program multiple times, or have forgotten to close one instance of it prior to re-running it from Eclipse?
One thing, that is not very obvious when using Eclipse, is that it allows to run any number of instances of Java programs simultaneously. When you have the Console view active, you have the option to terminate the latest launch.
To switch the console to a different launch (if there are multiple running) you can select from a list, by pressing the "Display Selected Console" icon, which is the monitor icon to the top-right in the Console view.
You can also remove any and all terminated launch console outputs from the Console view, by pressing "Remove All Terminated Launches", if every launch have been terminated it should now display "No consoles to display at this time", otherwise the next-newest running launch will be brought to the top.
If this isn't the problem, and indeed Eclipse have lost track of a launch (which is quite rare, but can happen - especially if you spawn sub processes yourself), you can safely terminate any run-amock java.exe process from the Task Manager, as Eclipse runs wrapped in a Windows executable on the Windows platform.
Java applications run under "java.exe", so you can look for that in the task list. Sadly, if several Java applications are running at the same time, it's hard to tell which is which.
I'm not terribly familiar with Eclipse, but it seems like Eclipse should tell your old version to terminate when you close Eclipse. The JVM doesn't cache past versions.
Hope this helps.
I had a problem like this as well. I would try to run the program after making changes, and it would run the older version of it, and still report errors and stop on lines that I had even commented out. I tried micdah's solution, but there were no java.exe processes in Task Manager. I solved the problem by killing the Eclipse process from the Task Manager, which closed the program without saving Eclipse Workspace settings. When I relaunched, everything I had saved in the .java files launched normally.
Could be a bug in Eclipse. Could be some code in your application that's spawning a new process. Impossible to tell from over here.
If you haven't already, check out the jps tool, which is included with the regular JDK. It might make it easier to diagnose the problem.