Office Hours — Today, April 21

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Apr 21
7:25 PM
Mark M.
has entered the room
Mark M.
turned on guest access
Ed T.
has entered the room
Ed T.
good evening Mark!
Mark M.
actually, I'm on the road, so it is morning here :-)
Ed T.
yikes
India?
Mark M.
Southeast Asia
Ed T.
brb neighbor looking for me...
7:30 PM
bill
has entered the room
Mark M.
hello, bill!
how can I help you today?
bill
hello Mrk
Alex
has entered the room
bill
It has to do with this issue https://github.com/square/okhttp/issues/2646
Mark M.
(BTW, hello Alex -- I will be with you shortly!)
Alex
No rush!
Mark M.
bill: OK
bill
I want to use self signed certifications with OkHttp
And I receive the error "tm is an instance of ... which is not a supported type of X509TrustManager"
Mark M.
are you following this recipe: https://github.com/square/okhttp/wiki/HTTPS#cus... ?
Ed T.
back
back of the line if fine.... cheers
Mark M.
(Ed: I'll turn back to you after bill and Alex!)
7:35 PM
bill
Mark, now I will study the recipe and later I will be back. Thanks!!!
Mark M.
OK -- I'll take questions from the others, and I'll be back with you shortly
Alex: your turn! do you have a question?
Alex
Ed, you can go before me. I'm about to eat
Passing my turn to Ed
Mark M.
OK... Ed: do you have a question?
Alex
Going AFK for now
Mark M.
OK, if anyone is around and has a question, go right ahead
Ed T.
I have a PDF question
7:40 PM
Mark M.
fire away!
Ed T.
pdf.js looks like my best bet... after reading your book
I don't need to support anything before API 19
the example uses embedded PDF files
Mark M.
OK, though bear in mind that my copy of PDF.js is probably a year or two old
Ed T.
if I pull a PDF from a URL do I need to save it to temp storage first?
Mark M.
I suspect that the answer is no, but I am not completely certain
Ed T.
ok
your example code was....
Mark M.
I did not test that scenario (or if I did, I forget the result)
Ed T.
View paste 
private void loadPdf(String name) {
    chosenAsset=name;
    loadPdfUri("file:///android_asset/"+name);
  }

  private void loadPdfUri(String uri) {
    try {
      wv.loadUrl("file:///android_asset/pdfjs/web/viewer.html?file="+
        URLEncoder.encode(uri, "UTF-8"));
    }
    catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    }
  }
I didn't see anything for that in your book
and from our last meeting... fyi
seeker has a boolean called 'user'
to separate event created from code versus the UI
and that was how I solved my 'event storm' issue
Mark M.
OK
Ed T.
safe travels!
Mark M.
thanks!
Ed T.
thank you sir
Mark M.
OK, if anyone has a question, go ahead, as I'm not sure who is around with questions at the moment...
Ed T.
has left the room
7:45 PM
Alex
Still eating, how are you doing Mark?
Mark M.
OK, and yourself? besides presumably being less hungry now... :-)
Alex
I've been very sick, but as soon as the antibiotics kicked in I've been studying everything Android
Mark M.
I hope you get to feeling better soon
Alex
I recently just learned about architecture patterns but its such a new idea I don't really know what to make of it or what does it mean practically in my own projects
Mark M.
if you mean GUI architecture patterns -- using abbreviations like "MVC", "MVP", "MVVM", "MVI", and so on -- I cover those in "Android's Architecture Components"
I can try to answer your questions about GUI architecture patterns, but you might want to read those chapters first
7:50 PM
Alex
Yes, and also something "clean architecture"
Mark M.
I mention clean architecture in passing in one of the testing chapters in "The Busy Coder's Guide to Android Development"
Alex
I see, I'm firing up the pdf to find the chapter you mentioned earlier
Yea I guess it just seems unfitting that I just keep creating classes in the java folder and just let it get messy. I wonder how others organize that stuff, separating logic classes from activity classes
Mark M.
well, in terms of folders, you are welcome to create sub-packages as you see fit
the extended MVI samples presently in "Android's Architecture Components" use separate sub-packages for the UI versus the rest of the implementation
clean architecture is not concerned with package names, but rather with roles
Alex
The file is big, is there a page number? If I Ctrl-F the title I'll crash Apple Preview
Mark M.
hold on
7:55 PM
Mark M.
it's in the Unit Testing chapter
in Version 8.11, the clean architecture material starts at page 1122
Alex
Great, found it
How come fragment tab layout with viewpager dont work with constraint layout?
Mark M.
um, it should
(BTW, bill: if you have another question, let me know)
Alex
I built mine using LinearLayout. But after reading the Constraint Layout chapter, I wanted to master it. And switched my main activity which housed my tab and viewpager widget xml.
But when I ran the app, the tabs disappeared and there was a visual glitch
bill
I have n't use the recipe of OkHttp
Mark M.
bill: try using their approach for custom certificates, and see if that helps you with your self-signed certificate
Alex: I do not know of any problem with using any flavor of tabs, ViewPager, and ConstraintLayout
but, if you have a layout file that you can show me, perhaps I'll spot something
8:00 PM
bill
I had use a general example which I adapted to OkHttp, and I received the mentioned before error
Alex
Let me create a gist
Actually better yet, have you ever made a sample project that implemented a TabViewPagerContraint?
I ended up going ahead with LinearLayout on my project so I have nothing to throw into the gist
Mark M.
I don't know what TabViewPagerConstraint is, sorry
bill
I saw in square/okhttp issues that you had started the issue with the specific error. I think that I MUST follow your advice and implement their recipe!!
Alex
Sorry that's just what I call a Fragment layout that implements XML Constraint layout with Tabs and Viewpager
I don't know any real short hand to describe it
Mark M.
I don't think that I have an example that wraps a ViewPager in a ConstraintLayout, sorry
Alex
No worries, I'll just make a playground file to get it to work
Just about every example uses LinearLayout for some reason
Mark M.
well, ViewPager was introduced long before ConstraintLayout
and some developers are switching away from ViewPager to other solutions, such as RecyclerView
8:05 PM
Alex
To be honest, I don't fully understand what ViewPager is
Is that what allows fragments to slide to the left and right?
Mark M.
there's a couple of chapters on it in "The Busy Coder's Guide...", but yes, that's the original swipe-a-page-at-a-time solution in Android
a typical implementation uses fragments for pages, though that's not strictly required
Alex
And RecyclerView is replacing that?
Mark M.
it's more that RecyclerView can be used as a swipe-a-page-at-a-time solution as well
Alex
I wasn't aware it had swipe functionality, I have yet to read that chapter
Mark M.
it has some useful characteristics compared to ViewPager, but it has less support for things like tabs
Alex
That's unfortunate. I really need the tabs.
Mark M.
my Advanced RecyclerView chapter works through a bunch of ViewPager-workalike scenarios with RecyclerView, including tabs
however, with RecyclerView, the pages are views, not fragments
so, if you already have working ViewPager code, you might just stick with that for now
only change if you have a concrete reason to do so
Alex
Yea I'll stick with it. Good, I'll put that on the reading list. And hmm interesting, I'll hold off on more questions on this until I have read these chapters.
8:10 PM
Mark M.
if either of you have additional questions, go right ahead!
Alex
Yea I'm full of them, I've been waiting all week
Just taking in some more food haha
Mark M.
sorry, I'm on travel this week, and that tends to scramble my office hours schedule
Alex
Thats fine, I've been sick for the past 2 weeks but my mind has been always thinking
Mark M.
well, that's good, because if your mind stops thinking... that's far less good
Alex
Haha well I'd hope my body throws an exception
Mark M.
only do that if you have a qualified medical exception handler in place
8:15 PM
Mark M.
I also recommend logging the stack trace, though please do so somewhere private, because ew
Alex
Hahaha good one
But now that I'm closer to completion of this certain piece of my app (i'm making a fitness app for my own use). I've been thinking about the "workout" part of my app on a layout and logic end. But I'll worry about the layout first
Lets say you click a button on the mainactivity to start a new workout. You are taken to a new activity. The layout of this workout activity is a LinearLayout and within it are nested LinearLayouts (with a custom drawable background) to make it look more like a card: these represent each exercise.
But would I need to put this into a ScrollView or RecyclerView to account for screen overflow?
Mark M.
that's probably a good idea
8:20 PM
Mark M.
also note that there is a CardView for making things with a card background
Alex
So the XML higherarchy would look like LinearLayout (global) > ScrollView -> LinearLayout (exercise) x nExercisesInWorkout
And then a button to finish or cancel the workout below all of this
Mark M.
ScrollView only has one child
Alex
Oh?
Mark M.
which represents the area to be scrolled
one typical solution is to wrap the whole thing in the ScrollView
Alex
I use LinearLayouts as visual cards. Is that not a good way to do it?
Ohhh
So would ScrollView be the outermost element in the xml
Mark M.
right
Alex
I see
Mark M.
if there are things that you want always visible, either make them be action bar items, or you will need an outer container that holds those things plus your ScrollView
Alex
I see
Okay, I think I have a good idea on how to go about the design of this. Now I have to think about the logic. It's still fuzzy.
Mark M.
for your exercises, if there will be lots of those, then a RecyclerView instead of ScrollView+LinearLayout may be worthwhile
Alex
Yea another reason to really get into the RecyclerView stuff
Mark M.
if there will only be a few exercises, and you prefer the ScrollView+LinearLayout approach, that's fine
Alex
Well the largest workout would typically have about 7 workouts, which would definitely overflow the screen
That would be an upper body workout. Leg workouts are generally shorter workouts
Mark M.
yes, but that's not so many that the recycling aspect would be necessary
Alex
7 exercises*
8:25 PM
Alex
Right, so I guess the question is. Does the finite (small) number of exercises per workout merit recycler view
Mark M.
probably not
though there's nothing wrong with using one
Alex
Of course.
Mark M.
for that number, go with whatever makes you more comfortasble
er, comfortable
Alex
Sounds like plan. Now all I got to worry about is the logic of how Workouts are persisted and organized
Mark M.
typically, if the contents of the layout are hard-coded, the ScrollView approach is the easier one, but if the contents of the layout are dynamic (e.g., determined by database I/O), the RecyclerView approach is the easier one
8:30 PM
Alex
Oh then I would need a RecyclerView I think. I haven't even thought about how to do a database yet, I'm about to read that chapter tonight. But in my mind, I believe that there will be "Tracks" which would be an object that would have "exercises" as well as predefined set,rep, rest time information.
Mark M.
OK, that's a wrap for today's office hours chat
the transcript will be posted to https://commonsware.com/office-hours/ shortly
Alex
:)
Until next time
Mark M.
the next chat is Tuesday at 4pm US Eastern
have a pleasant day!
bill
good day
bill
has left the room
Alex
has left the room
Mark M.
turned off guest access

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Office Hours

People in this transcript

  • Alex
  • bill
  • Ed Tidwell
  • Mark Murphy