How to Pass Commandline Arguments and Properties

[schrieveslaach]

Is it possible to pass command line arguments to Java configurations? And is it possible to pass JVM properties?

[mfussenegger]

You can add args and vmArgs. See https://github.com/microsoft/java-debug/blob/625fe84cef4825a4b6b476d04383f5168e81708d/com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/protocol/Requests.java#L104-L119

Not sure if there is also proper documentation for it somewhere.

Here is an example of it being used: https://github.com/crate/crate/blob/e1dea641515e57f61e77dcd34d8b2de042878bbf/.vscode/launch.json#L4-L13

And I recommend to use it with nvim-jdtls, otherwise you need to also define the full classpath and so on.

[mfussenegger]

Created a PR to document them: microsoft/java-debug#412

[schrieveslaach]

Thanks. I did not find it in the documentation (not in nvim-jdtls' or in nvim-dap) so i wasn't aware of these options.

A follow-up question: is it possible to configure them for a one shot start? I could imaging that continue() has a list of args for one shot debugging, e.g. require('dap').continue({ args: {"a", "list", "of", "args"}})

[mfussenegger]

You can either use a function as value in the configuration (if done in lua) and use inputlist/input to prompt for arguments ad-hoc or otherwise you have to call require('dap').run(config) with an ad-hoc configuration that you created.

[abenz1267]

Just gonna hijack this because it's somewhat related: i'm trying to get nvim-dap to work with jmockit, apparently as of JMockit 1.42 it requires a -javaagent jvm init parameter (see also here https://jmockit.github.io/tutorial/Introduction.html#runningTests).

I've tried adding it like this:

    dap.configurations.java = {
        request = "launch",
        type = "java",
        vmArgs = "-javaagent:/home/andrej/.m2/repository/org/jmockit/jmockit/1.49/jmockit-1.49.jar"
    }

Is this correct? I can't get it to work properly. Tests run fine via Maven. A dependency annotated with @Tested stays null when running in nvim and i suspect it's because of the -javaagent setting.

Regards

[schrieveslaach]

I think you need to hook into require('jdtls').test_class() because that will create a Lua table that will be passed to require('dap').run(config_generated_by_jdtls_test_class). I'm not sure how you can do this but I hooked into nvim-jdtls to modify the run configuration:

local M = {}

M.run_with_extra_jvm_args = function()
   local dap = require('dap')
   local configurations = dap.configurations or {}

   if configurations.java then
      vim.ui.select(configurations.java, {
         prompt = 'Select Java Main',
         format_item = function(item)
            return item.name
         end,
      }, function(choice)
         local config = vim.deepcopy(choice)
         config.vmArgs = 'My custom choice'
         dap.run(config)
      end)
   else
      print('No Java configurations available. Please, run JdtRefreshDebugConfigs')
   end
end

return M

[mfussenegger]

You can pass config_overrides if you call jdtls.test_class or if you call setup_dap_main_class_configs / fetch_main_configs.

E.g.:

require('jdtls.dap').setup_dap_main_class_configs({ config_overrides = { vmArgs = 'my-custom-args' }})

Should work.
mfussenegger/nvim-jdtls#277 also added some API reference documentation.