hello, Scott!

how can I help you today>

er, today?

Hey Mark

well I was just coming to the site to see if one of the resources talked about Navigation

I saw that office hours were live so I popped in.

I cover some of the basics of the Navigation component in *Elements of Android Jetpack*

and the app built in the tutorials in *Exploring Android* also uses navigation

does it use androidx.navigation.safeargs?

yes

ok so I just tried implementing that following the d.android.com guide, and I'm completely lost

it says it should generate some code for me, but I don't see what triggers the generation or where the code would be.

there is a plugin that you add to your Gradle build file

got it

that will examine your navigation resources and generate classes for them

ok I have a nav_graph.xml with 3 fragments and 2 actions connecting them

the origin of each action gets a ...Directions class (e.g., RosterListFragmentDirections), with methods for each action starting at that origin, with the method names based on the action IDs

I'm assuming I've set this up wrong then. So, if I fix it, how does safeargs know to try and generate the code again

?

I would hope it does it automatically -- worst-case, clean and rebuild the project from the Android Studio Build menu

would the files be in app/src/main/java/com.whatever/?

well, they are code-generated, so they will be in build/ somewhere

the ...Directions class should be in the same package as is the origin fragment class

I see

for example, in https://gitlab.com/commonsguy/cw-jetpack-kotlin..., I refer to a ListFragmentDirections class, and I do not need an import for it, as it is in the same package as is ListFragment itself

ok

similarly, there will be an ...Args class generated for each destination (see https://gitlab.com/commonsguy/cw-jetpack-kotlin... and its use of DisplayFragmentArgs and navArgs())

the chapter for those samples is https://wares.commonsware.com/app/internal/book...

the chat is just about over -- any last questions?

ah sorry I was reading

yeah 1 question

"A class to help code wishing to navigate to that screen provide the data, with the expected data types"

this is in that chapter

is that sentence correct? If so, what is code wishing?

that sentence is a bit awkward, but I'd need to see it in context

if you want to navigate from ListFragment to DisplayFragment, you use a ListFragmentDirections class

ok. well I'll get to reading through this stuff. Thanks for the help!

that will have static methods based on action IDs

and those static methods take parameters based on the action's arguments

where the parameter types are determined by how those action arguments are configured on the action

sorry -- the arguments are on the destination, not the action

so, for example, see https://gitlab.com/commonsguy/cw-jetpack-kotlin... -- the displayFragment takes a modelId argument that is of type String

so, the displayModel() method on ListFragmentDirections takes a String parameter to supply as the argument to DisplayFragment

and... that's a wrap for today's chat

ok

the transcript will go up on https://commonsware.com/office-hours/ shortyl

er, shortly

the next chat is Thursday at 7:30pm US Eastern

thank you. I'm starting to get it

good to hear!

and, have a pleasant day!

ok. Thank you thank you. Have a good day!