IntelliJ IDEA Scala plugin includes a number of settings that let you affect how your Scala code is being debugged.
- Press Ctrl+Alt+S to open the Settings Dialog
- Expand Debugger
- Click Scala
Here you can tell the debugger not to step into auxiliary Scala classes during debugging.
This is handy for newcomers who are not very not familiar with Scala internals.
Select the option Do not step into specific Scala classes to exclude all classes with qualified names beginning with scala.runtime.* from debugging.
You can create a number of custom filters that exclude certain classes from debugging.
For that, click Stepping under Debugger. This opens a dialog where you can add, edit, remove, enable and disable custom class name patterns of the classes that should be excluded from the debugging process.