recommended IDE for developing openjdk?

Jan Lahoda jan.lahoda at
Mon Jan 18 13:42:48 UTC 2021


For recent Apache NetBeans (12.2):

Opening the (Java) modules of the OpenJDK:
-have the OpenJDK configured, ideally with `--with-jtreg` (not 
mandatory, but better), and built (not mandatory, but better)
-run NetBeans, ideally on a JDK 15
-(a bug workaround, this only needs to be done once, sorry for that): 
activate Java: in the main menu, do File/New Project, select any Java 
project, click next, and on a panel saying Java SE needs to be 
activated, press Activate, and when that is done, cancel the wizard
-then the Java modules of OpenJDK can be opened as project, do File/Open 
Project and select e.g. src/java.base, src/jdk.compiler, src/jdk.jshell, ...
-tests under "test/jdk" will be available in under the java.base 
module/project, tests under test/langtools will be available under the 
java.compiler project

There is a certain level of settings under Project Properties of the 
projects, like location of jtreg, if it is not specified during 

There is also a limited support for the C/C++ sources, based on ccls 
and/or clangd.


On 18. 01. 21 12:11, Maurizio Cimadamore wrote:
> Hi,
> thanks for the pointer to the Eclipse project - I'm sure folks will find 
> that useful.
> I think these days the IntelliJ support is relatively polished - there 
> are features missing yes (for instance the project is monolitic, and not 
> modularized, but folks here are using it pretty regularly and I can't 
> say that has been a huge issue so far).
> To get started with intellij you have to create an IDE configuration first.
> 1. first run `sh configure` as you normally would to set up your JDK 
> build - that build configuration would then be reused by Intellij
> 2. then run `sh bin/ <list of module names> - e.g. `sh 
> bin/ java.base jdk.compiler java.desktop` - this will create an 
> `.idea` folder in the current directory and set the sources for the JDK 
> modules you specified.
> 3. open IntelliJ and point it to the folder where the `.idea` folder has 
> been created. If everything worked correctly you should have a project 
> up and running.
> The base project supports actions for cleaning, rebuilding the selected 
> modules, or building a JDK image.
> Optionally, you can also build and install a jtreg plugin, to run and 
> debug tests:
> I use this setup on a daily basis and I think it works pretty well - 
> there are things that can be improved (for instance, I don't think the 
> generated sources are always recognized correctly, we need to look into 
> that), but I'm quite productive with it (especially with the jtreg 
> plugin enabled).
> I know that there is also some limited support for VSCode (especially 
> for hotspot development):
> And that there is Netbeans support as well - CC'ing Jan who knows more 
> than I do on how to get started there.
> Eventually we should collect all this info in a single place, but I 
> never found the time to do so. Apologies!
> Cheers
> Maurizio
> On 18/01/2021 09:46, Langer, Christoph wrote:
>> Hi Clemens,
>> while I won't argue about the fanciness of the Eclipse user interface 
>> (��), I'd like to point you to a set of Eclipse projects that I 
>> created nevertheless...
>> You'll find them here: 
>> The main benefit of these Eclipse projects is that the projects for 
>> all modules and tests are linked together so you will immediately 
>> recognize errors in dependencies. I think that doesn't work so well 
>> with IntelliJ.
>> Another hint: There's a mailing list called ide-support-dev where 
>> questions around IDE support can get discussed.
>> Best regards
>> Christoph
>>> -----Original Message-----
>>> From: discuss <discuss-retn at> On Behalf Of Clemens
>>> Eisserer
>>> Sent: Freitag, 15. Januar 2021 21:33
>>> To: discuss at
>>> Subject: recommended IDE for developing openjdk?
>>> Hi,
>>> About 10 years ago I used eclipse to work on OpenJDK, however I would 
>>> like
>>> to get rid of it because of its slow/ugly user interface.
>>> I wonder, are there any recommendations which IDE to use these days?
>>> I gave IntelliJ a try but having not used it that much (except for some
>>> fairly standard maven based projects) I failed to configure it 
>>> correctly,
>>> however I haven't tried Netbeans still.
>>> So to make it short: Which IDE is known to cope well with working on the
>>> OpenJDK codebase?
>>> And are there detailed instructions available for creating an openjdk
>>> project with intellij?
>>> Or would I be better off using netbeans?
>>> Thank, Clemens

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