Scenario
I am working on a big application consist of hundred of class files. As part of giving a patch to fix the issue in production set up, we generally give a jar file. This jar file contains the class file(s) which includes a fix and put inside one patch path(This is the path which is used to put the patches/fixes as jar file). In the production set up, we recommend to restart the application. As part of restart , application first looks the class files from patch path and then from the other path where all the class files are present. So this way first classes from patch path is loaded.
Expectation
Now instead of restarting the application, i want to reload the class file so that restart of application can be avoided. I checked in net and found the following:
We can use customize/dynamic class loader as well. I think this is also not full proof way of doing it.
URLClassLoader is also one of the option.
If we use customize class loader, then we have to load all the application class files using this because class file can refer to another class file if it is loaded from the same class loader. This is what i read from net. If yes, then i think this option is not valid. right ?
After checking all the above options, i still feel the above options are not good enough to load the existing class file (which is getting used in running application as well) at run time.
So question arises that is there any full proof possibily to replace the class file at run time for java application.
if Yes, Could you please guide in this regard.
Also, if this kind of requirement or question is already answered properly(I didn't find any good link), please redirect
NOTE: I think OSGi is also one option. But i feel not possible in such a big application since it will requires lot of changes which i want to avoid.
Please suggest.
This is in reference to the question posted at org.netbeans.validation.api.ui.ValidationGroup.add() - How to specify ValidationStrategy?
I am trying to do something similar. Please guide me on what needs to be changed and where. I went through the given links but couldn't find the relevant info.
P.S.: Asking in a separate question because I can't comment on the original one due to lack of reputation points.
Regards
Uday
I found out what was required.
Check out the code from their repository (https://svn.kenai.com/svn/simplevalidation~src) and open ValidationAPI as a project in Netbeans (or whatever IDE you're using).
To change the default validation strategy you'll need to make the changes in ValidationGroup and SwingValidationGroup classes under org.netbeans.validation.api.ui and org.netbeans.validation.api.ui.swing respectively.
In these classes find ValidationStrategy.DEFAULT and replace it with the strategy you want (INPUT_VERIFIER, ON_FOCUS_LOSS, ON_CHANGE_OR_ACTION).
Build the project to generate a new jar and incorporate that jar in your own project.
That's it.
I am using Resource Change Listener to track the changes done to my project. Out of these changes i want know if the change was done via Eclipse menu or some other eclipse plugin or if it was typed in by user. Please suggest a way to achieve this.
I am not sure whether there is a direct API to to that, because the interface IResourceDelta that it mainly implements does not have a method on who modified the resource.
You can track most the changes mainly on the resource it modified, but 'who' modified it is an unanswered question for me too. I found this resource useful in this regards,
http://www.eclipse.org/articles/Article-Resource-deltas/resource-deltas.html
I use Eclipse to write Java code and use DropBox to sync my code with others' across our multiple computers. Most of the time, everything works as expected: if anyone makes a change on either end, the change is saved and when the other person refreshes the Eclipse workspace, the changes come through and can be viewed and run successfully.
Sometimes, one of several errors arises. Sometimes Eclipse says it cannot find a main class and sometimes it says it could not find the class itself. Sometimes it will not report an error but for some reason will not actually update the .class file and therefore run an old version even though the compiler displays the new source code and that saves. I've then noticed that if I manually copy the code into a new .java file elsewhere in the file system and then compile it, it works fine, but for some reason it refuses to regenerate the .class file and I have to delete it manually and replace it with the one generated in the other project--then it works. But for solving the other problems everything needs to be manually copied, deleted, and re-pasted....
[The actual errors include NoClassDefFoundError, UnsupportedClassVersionError, and some other error related to not having a main class.]
I realize that the description here is somewhat vague, but unfortunately I'm not entirely sure what's going on. I hope I'm just missing some basic fact that would help solve all these problems.
Thanks!
I'm sure you will see issues using Dropbox for sharing your source.
Eclipse does not know what Dropbox is doing whilst it's uploading and downloading updates and their activities will certainly not be synchronised. At arbitrary points in time when Eclipse tries to do builds etc. it will find unexpected activity going on, maybe even partially downloaded source files which might explain the specific errors you are seeing.
You're trying to do something more complex than sharing photos or documents. The advice I would give is to use a source control system like git or subversion for source code sharing and control. You can then make use of plugins for Eclipse that are designed to integrate these systems in an easy to use way. There's a learning curve there, but the skills will serve you well.
You can use online versions of these solutions like github and unfuddle if you want to consume sharing, backup and version control of source as a service like you do with Dropbox. They're free, too.
Subversion, Git and all version control software solve all of these problems for you.
Dropbox is not really an adapted system for sharing code. What you should do is set up a SVN, and commit only the source files. This way, you won't have these kind of errors.
Dropbox does have versioning (you can restore old versions of a file), and doesn't seem to be a horrible solution for the problem. I keep my Eclipse repository on Dropbox so it is available on any computer; but since I only use it myself, I haven't encountered your problems.
There is one case I can absolutely see you running into problems--it's if your class files are stored in the dropbox as well. This would just screw everything up. Make sure you specify a location on your local hard-drive for all build artifacts (classes, jars, ...) and that the only thing on your dropbox is the .java sources.
In fact, I suggest you don't keep your eclipse project in your dropbox, just create your eclipse project and point it to the java files in your dropbox.
If this doesn't work for you, go with what other people here said and set up a SVN repository somewhere, it's easier than you would think.
Oh, another possible problem--dates! You may want to make sure the date on your java files isn't jumping forwards and backwards (as might happen if one of your developers were in another time zone). In this case, Eclipse may prefer not to re-compile your file.
Also, instead of the copy/etc procedure you are currently going through, try forcing a project clean.
Response to request for more info:
When you start Eclipse, select/create a workspace that is NOT on your dropbox. The best place is probably off your home directory. If you have already specified a default workspace, there should be a switch workspace item in the file menu.
Create your project. select "Create project from existing source" and specify the source files in your dropbox. I think you want "create separate folders for source and class files" to keep your class files out of your dropbox. If you see anything saying "Copy files into your workspace, say "no".
This should give you a valid, working project. I hope you don't see those problems any more.
One more thing may help--and this may work on your existing project--without the above procedure...
Whenever you refresh your files (f5) to load in changes from the dropbox, select the Project/clean menu and select the project. This should delete all the class files and rebuild them.
If your classfiles are shared on the dropbox, this could still have strange consequences on other people with eclipse open, so I really do suggest rebuilding your workspace as I said above.
How to avoid no main class
Provide one. That issue has nothing to do with DropBox
I have a very specific question.
I want to compile an ActionScript project within Java in-memory with the help of the Flex Compiler API ( http://livedocs.adobe.com/flex/3/compilerAPI_flex3.pdf ).
My last problem is to add images (jpg, png) that are embedded in the project to the compiler. I don´t see a possibility to do this in-memory and my attempt to add them from disk was also unsuccessful.
Hope someone has a good hint for me.
Greets, Konsumierer
Invoking the flex compiler from java shouldn't be any different from invoking it from the eclipse plugin. I suppose you have the project located somewhere on the filesystem, so I suppose if the images are in the correct relative path, they should be embedded. How do you embed them, actually?
Another option is, in case when you use them in web-environment (and not AIR), to just write a relative server path to the image. For instance - the .swf is in /, you can poing the image to /images/myimage.jpg, and it will work.