Develop Reference

IntelliJ IDEA doesn't redeploy changes

I have a Spring Web application and when I debug with IDEA's debbuger in Tomcat and redeploy the project after some changes, the changes are not deployed and debugger "sees" the old code (stepping through wrong or empty lines). Only thing that helps is to run maven clean install and then start the Tomcat again.
I tried clearing IDEA caches but it didn't help.
Hotswap also doesn't work, although I have correct options selected in settings, but I can live with that.
Note that I use redeploy not hotswap, so the whole application is started again, it should reload all classes but it doesn't. Only after maven build it works.
Note 2: I think it work ok one month ago, but no changes I can think of could do this (project- or IDEA-wise)
EDIT: So hotswap is now working OK (magically, I didn't do anything). But when I make larger modifications (eg. method signature change, etc), they are not picked up during REDEPLOY to the server. So I neeed to run maven clean install and start the server again to see the changes and for hotswap to work properly after method body modifications on this new code. Any idea why?

You need to check your run configurations of tomcat, in "Before launch" there should be Make and Build artifact steps, also be sure that all you changed classes are really compiling during redeploy - this is the place I would start from.
Also I don't get why you use redeploy instead of hot-swap? Redeploy is usually same time-consuming as restart server, but hot-swap is nearly instant. Though it allows only to change method bodies and constants, usually it's much prefferable then redeploy in development. Personally I'm using JRebel which is free for non-commercial projects now and restart server very rare.
EDIT:
I don't know why your classes are old even after redeploy, but the reason is 99% that they do not compile after changes into exploded folder. Doing maven clean install after each code change is too much (IDE compilation should be enough).
What I can suggest you is not to redeploy but to restart server after big changes. So that IDE perform Make, Build artifact and Deploy artifact tasks.

In addition to david.lucky hints, make sure that on your Tomcat configuration in the deployment section you're using an exploded artifact

I had exactly the same problem! I've spent hours in solving this issue.
I don't know why, but the solution for me was that (I'm working on MacOS High Sierra):
First, I had some of my tutorial projects, I was working on, on my Desktop in a folder /Desktop/tutorial/... These project were working fine. I could redeploy and Tomcat was recognizing the changes in my java files.
Then I started some new, own projects, and I placed them in my home directory, something like /Users/myHomeDirectory/WebApps/.
I could build and run these objects, but when I made changes, I had the same exact problem, that Tomcat was not recognizing the result. Only thing that helped out, when I clicked Maven-Button "Reimport all Maven Projects".
I tried really lots of different things. Nothing worked.
Then I thought, maybe, theres something wrong with my project. So I took one of my projects from Desktop and copied them into my home directory. But suddenly, I had again the same problem.
So here's my solution: I created a new project on Desktop again. And I don't know why, but now it's working fine. I really have no clue why. And believe me, I did not change any settings. I did exactly the same!
And regarding the life reload without redeploying. This works really fine for me (without any plugins like JREbel):
Go Run –> Edit Configurations –> “Deployment” tab, clicks + icon –> select an “exploded artifact”
Select “Server” tab, update the following options :
On ‘Update’ action -> Update classes and resources
On frame deactivation -> Update classes and resources
Run web application in Debug mode. Try to modify some codes or resources (Java files, ...), the modified classes and resources will be reloaded automatically.

This has been happening me for some time now Ultimate Edition after switching from eclipse to Intellij a few months ago.
Standard tomcat config and debug settings mentioned above used.
Intellij will show green popup after nothing to reload or reloaded one class.
Yet the debuggers bytecode is not the same reloaded/updated code.
You can force a recompile which will work for small changes ctr shift F9.
Other than that a clean install seems to work for annotation, method definition changes etc. If you try a recompile the debugger will fail the server.
So the answer is ctrl shift F9 on the file you change

Glassfish 4 take long time to deploy

I have Glassfish 4.0, on windows 7 and netbeans 8
when I try to deploy java EE application, sometimes the deploy time takes 2-3 seconds, and sometimes it lasts forever!!!!
I have to kill the java.exe from the task manager in order to make it work again, sometimes this solution does not success and I have to restart my PC.
I tried to remove the glassfish from netbeans and adding it again, but with no result,
I tried to change the windows to XP, with no result,
I tried to change the whole PC with no result also....
I am still having this problem and I cant go on LIVE server if I cant fix this on the development machine.
please any advice?

I have fixed this issue by creating new project, then I put the "web" and "src" folder from my old project.
the glass fish now deploy fast.
I found the cause for this, its that I work with a team and we share the same build files from our different PCs, so after removing the build files everything work good.
it happened because we use SVN to share the code.

Sudden weird errors on a project

Today I came to work, happy. But when I opened my Eclipse, I saw that one of my projects has errors.It's weird because it shows that it has errors only in the window bar, and not in the Navigator. I don't have any Java errors, this is a valid project that was fine all the time:
Some of the errors on the error log of Eclipse:
JavaBuilder handling ImageBuilderInternalException while building: SP_Procedure
Cannot connect to VM
File <SomeFile> has been skipped, problem while reading ('Resource is out of sync with the file system')
Unhandled event loop exception
Internal error
When I run an application from this project, I get a warning message but when I proceed, it works fine, but still. It's very disturbing and I'm not sure if it's harmless.
I tried to:
Restart Eclipse
Restart my machine
Clean projects and recompiling them.
Refresh projects
Pray
Nothing helped. What could be the problem? (I'm using Indigo Service Release 2)

The following nuclear option has desperation written all over it. But I have been where the OP has been with the Juno version of Eclipse.
Run a "Synchronize with Repository" and save all of your local updates to a different directory.
Delete the project. (Check the box to delete the contents on disk. Scary step, but that's OK, because you saved it in a different directory in the previous step, right?)
Read in a fresh project from the repository. It builds happily at this point.
Integrate your local updates.
Keep on praying.

Looks that one unused JAR was deleted, but for some reason, I didn't get errors in any file, even in the files that imports this JAR! So what I did was restoring this JAR, delete unused imports and deleted the JAR again.
I've found this error after two days of navigating on this project on each file.. This is weird that Eclipse didn't recognize that1 this is an error, and throw many unrelated errors such as:
Cannot connect to VM
File has been skipped, problem while reading ('Resource is out of sync with the file system')
Unhandled event loop exception
Is this a bug in Eclipse? (All errors and warnings are enabled!)
1 As seen in the image in the question..

A class from the list of imports for the file seems to have moved out or the jar file containing the class is missing.
Expand the imports section and check if you find some classes that are missing but have been imported.

Though it is a pain, sometimes the easiest solution is to back up all your projects (either in a repository or somewhere else on your computer) then uninstall and reinstall eclipse. No it's not fun, but it should reset eclipse so everything works again. The downfall though is that you have to reconfigure eclipse to any special settings you had/reinatall any extra functionality currently installed (eg. android add-on) and reconnect to any repositories you have. While punting isn't fun, it can be effective... I hope you don't have to resort to this though.

I have went through that problem a lot of times, and tried everything you tried. Rebuild, recompile, refresh, remove and add JDK, remove and reinstall Eclipse... nothing worked
The only thing I concluded is that the workspace metadata was corrupted.
What I did (every time it happened) was
Create an empty workspace
Import -> existing projects into worskpace
Mark the "copy projects" (else it will only link them)
Wait for the copy, and start working with the new workspace
If you work with SCM systems (Git, SVN, etc), making a full checkout will do the trick too, but the worskpace import will let you retrieve those changes you didn't get to commit (if any).
It's a little painful if you have somethings already set (like JDK names, servers, etc), but then I realized it was faster than keep searching how to fix the workspace
Regards!
PS : I've been working with Kepler lately, and everything works fine till now

Click Window -> Show View -> Other -> General -> Problems
This view will show you what is wrong.

Did you, by any chance, update your virtual machine outside of Eclipse? I can't help but feel that we're both missing a finer detail here. I just keep seeing "cannot connect to VM" and thinking that it's a major clue.
Have you tried running anything from the terminal? Does it work there?
If so, do you know where your current edition of Java is located? Is Eclipse looking somewhere else?
Is this exclusive to one project? Do you use any additional libraries to the JDK?

Maybe try this for Resource is out of sync with the file system error:
Right click project in Eclipse Package Explorer
Close Project.
Right click project in Eclipse Package Explorer
Open Project.

Other things not mentioned:
project properties > java build path, see if any of those tabs got changed, local file got moved? read/write permissions on some file you are linking to?
project properties > java compiler, see if workplace settings have changed? maybe under errors/warnings, you can systematically set them to 'ignore' until the error goes away to determine what type of error it is?
maybe update some of the eclipse plugins?

I saw something like this happening for a number of reasons. Mainly because of validation in files other Java source code. See if you are validating XML for instance.
Right click your project and chose Properties (Alt+Enter) and Validation to see the related configuration.
As for the danger, I lived with those marks for ages and nothing wrong ever happened.

Eclipse and JBoss not refreshing or rebuilding

I'm having this problem in eclipse (EE) when I change things in my code (even something as simple as the text I'm printing using println) it doesn't get applied. I'm using JBoss and when I rerun the servlet, nothing happens.
Any idea how I can force JBoss/Eclipse to do this? I can't preview anything so it's really annoying if I want to test some new code.
Thanks!

Eclipse publishes the newer versions of your application periodically (its called the automatic publish feature). Either the interval is too large, or you're not waiting sufficiently long enough for re-deployment, or automatic publishing of the application has been disabled.
Sometimes, despite ensuring the above, Eclipse might still not publish the newer classes, in which case you might want to perform a clean build, which causes the newly built classes to be loaded into JBoss.

Sorry to ask such a basic question: Do you save your changes before testing?
Eclipse uses its own compiler to check for syntax errors while you are editing, but you have to save the file before the edits take effect in the application.
I only ask because this could be confusing if you are new to Eclipse, having changed from a different IDE. File permission settings can also prevent your files from being saved or built.

Working on EJB deployed in JBoss with Eclipse IDE.
We have ANT build file, in which first old project is deleted from JBoss,
then compiling classes, & building proper directory structure & deploy as .ear - .sar again in JBoss directory.
Stop JBoss, run build file, start JBoss.
Its a good practice to have a build file to deploy project.

Eclipse keeps running my old web application

OMG - what is going on with Eclipse (3.3 Europa) - has anyone come accross this problem (bearing in mind I have been messing about with uninstalling different Tomat containers and installing others - but anyway thats another story)
When I change a line of code or remove a class within my project - when I come to debug - it actually goes to a line that is commented out and runs that line regardless!!!! e.g.
//System.out.println("you should not be able to read this!");
UPDATE: This can be solved by setting Project -> Build Automatically (see answer below).
REMAINING PROBLEM:
Eclipse is not keeping my hot deploy folder current with the latest changes to my project:
I found out to my horror that some old remenants of my project are 'hanging around' in the folder that I think Eclipse uses for hot deploys or something
C:\myJavaCode.metadata.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\myWebApp
basically it is not actually copying accross any changes made in the classes of my working dir!?!??
...anyway - in order to keep my project up to date - I have to modify this folder too - TOTALLY UNACCEPTABLE - as you can't develop in this way - it would take you eons! Anyway, if anyone can help explain to me what stupid thing I have done to get me in this mess and how I can get out of this mess - I would really appreciate it.

Have a look at:
Windows>Preferences>Server>Launching...
and:
Project>Build Automatically
maybe you accidentally disabled the auto-deploy features.

I had a similar problem, only without the added complexities of a web app. I'm just running a JUnit test and it's running the old code. I went into Configure Build Path, on the bottom of the Source tab, and looked at Default Output Folder, which said myproject/bin. The Package Explorer doesn't even show a bin folder, but when looking at the file system there's a bin folder there. I deleted the bin folder, refreshed the package explorer tree, and it worked. This behavior was in Helios and occurred with AND without Build Automatically selected...looks like a bug to me.
Dave

A super-silly question: Does all your webproject and related projects compile correctly?
Also check your output folder for classes (Project Properties -> Java Build Path -> Source Tab) then go to your filesystem and check permissions and modification dates.
Hope this will help you.

Probably the easiest way to get past this is to define a new server.
Right-click in the Servers window and select New, or when you do 'Run On Server' select Manually define a new server. You can have multiple servers defined using the same Tomcat runtime (they'll all have separate configs and deployment directories defined by -Dcatalina.base=...), but don't run them at the same time unless you change the ports they're listening on.
The new server will use a path like
<<yourEclipseWorkspace>>\.metadata\.plugins\org.eclipse.wst.server.core\tmp1
for the Tomcat conf and webapps directory.
Try running on this server. If it works, you can compare settings with the old one,
maybe try deleting the app from it and re-deploying, and figure out what you might have done to cause the problem. Or just delete the original server config.
As far as your second problem, I'm not sure. I'd try a new server config first, get it working, stop the server, do a 'Clean' on your project, delete anything in the tmp1\work\Catalina directory, and restart the server (you could remove and add your project to the server again too to be really clean).
Check the console messages too to make sure there were no errors related to this.