hello, Michael!

how can I help you today?

Hi Mark

In the book chapter Divider on RecyclerView

Drawable divider = getResources().getDrawable(R.drawable.item_divider);

Saw getDrawable deprecated

IIRC, there is a two-parameter version added in Android 5.0, taking a theme ID as the second parameter

that's not available in older versions of Android

I see.. So what's should be?

what I have is perfectly fine for the purposes of that app

"deprecated" means "there's something else that we think that you should consider using"

most stuff that is deprecated continues to work fine

great..

Another stuff, I'm creating an activity, with Toolbar, and some fragments inside

I have created a fragment transition, and worked on the 'content' which is the one inside Fragment Layout

I want to make the Toolbar also animating, for example the title change

But still not have any idea how to do that

I doubt that it is possible in any supported fashion

Toolbar does not expose its internal workings

I'm trying to put the toolbar inside the fragment, is it a good idea?

um, I cannot really answer that

Toolbar is designed to go wherever you want it

But then I will have a nested fragment.. Is it nested fragment recommended or not?

using a Toolbar does not require nested fragments

using a Toolbar does not require any fragments at all, for that matter

(BTW, Bob, I will be with you shortly!)

that being said, I am not a fan of nested fragments

I will go out of my way to avoid them

Agree.. Anyway I will let Bob to raise question first

Reading discussions on SO, I see that many people are using the Genymotion emulator. What are your thoughts on the adequacy of the stock emulators and the benefits of using one of the alternatives?

I have never used Genymotion, due to issues that I have had with their license agreement

Do you find that the stock emulators meet most of your needs?

I tend to use hardware more than emulators, but I have more hardware than does your average Android developer

Okay, thanks.

based on comments that I have seen, my sense is that Genymotion is an improvement over the stock emulators, and neither is as good as hardware

at least, when you have hardware for the scenario that you're trying to test

now, the Android Studio 2.0 emulator looked slick in the demos shown at the Android Developer Summit a few weeks ago

so they're obviously giving it a bit of attention

let me take another question from Michael, and I will be back with you in a bit

Michael: your turn! do you have another question?

OK, if either of you have a question, go right ahead

Yes, I've just had a nested fragment because I'm trying to create master-detail app in 1 activity

I've been learning more about TaskStackBuilder. In the docs, I've only seen it used with Notifications. Are you aware of other situations where TaskStackBuilder can be put to good use?

And also put ViewPager

Michael: remember that ViewPager does not necessarily require fragments, and neither does master-detail

fragments are typical ways of implementing those, but not the only way

Bob: I think it gets used for up navigation

I thought that ViewPager only works on Fragment.. Even if combining with tab layout also?

ViewPager uses a PagerAdapter

the PagerAdapter base class only knows about Views

the two concrete implementations of PagerAdapter in the support libraries use fragments

but PagerAdapter itself does not

in the book, I have at least one example of a fragment-less PagerAdapter

in the method public Fragment getItem, it should return Fragment right?

that is FragmentPagerAdapter or FragmentStatePagerAdapter that you are referring to

you do not have to use those implementations of PagerAdapter

ok, thanks, Mark

Btw, still not found the fragment-less PagerAdapter on the book

Thanks, Mark

see page 763 of Version 6.9 of the book

they are covered in a discussion of how to have more than one page visible in a ViewPager, as one way of making better use of larger screen sizes

Found it, thanks

Regarding the setHasOptionsMenu, is it only useful for modifying menu from fragment?

it is how a fragment indicates that wants to participate in the action bar

if a fragment does not need to do that, do not call setHasOptionsMenu(true)

(BTW, Bob, if you have other questions, chime in!)

Thanks Mark, just try that

I was recently trying to answer a question on SO that involved background service state, process management, and such. It eventually become clear the user's device was running Xiaomi MIUI and much of what I understood to be the standard Android behavior didn't apply. How far has MIUI diverged from Android? Is it even correct to still call it Android?

well, AFAIK, Xiaomi MIUI devices are not Google Play ecosystem devices, and therefore do not have to pass the Compatibility Test Suite

in theory, device manufacturers will aim to be close, if they want third-party developers to ship apps on their devices

so, Amazon was worse early on, but has been better in the second and subsequent generations of their Fire devices

in terms of Xiaomi specifically, I haven't picked up one of their devices to try it out, though I'm looking to do so

Got it, thanks.

it wouldn't surprise me if they have tinkered more than average

but I can't cite specific things where they have departed, as I lack direct experience

I have created a RecyclerView with a set of data (some fields, include an image). Each time the activity started it gathered from the server and put into the list of Model.

But when the app close and reopened, it's again download every data, including the images. How to manage this thing?

what exactly do you mean by "close and reopened"?

close the app and reopen the app

you don't really "close the app" in Android

so, what exactly do you mean by "close the app"?

do you mean "press the BACK button to destroy the foreground activity"?

yes

you are welcome to maintain some process-level data cache, typically in the form of a singleton

your process is not immediately terminated when the user destroys your last foreground activity

and so, if the user returns to your app fairly quickly, your cache can speed up presenting data to the user again

however, you need to take care, as any singleton amounts to an intentional memory leak

you do not want to start causing yourself OutOfMemoryErrors

So the singleton will still exist unless the user destroy the app from the settings?

no, the singleton will exist until the process gets terminated

that can happen at any moment while your app is in the background

once the user presses BACK or HOME, and you are no longer in the foreground, your process is eligible to be terminated, to free up system RAM for other apps

that may happen in milliseconds, seconds, minutes, or hours

it all depends on how much system RAM the device has, how busy the device is, etc.

should I add another 'layer' like SQLite?

you are certainly welcome to persist data to local files

that could be in the form of a second-level cache

or it could be that you work primarily with the local data, synchronizing data with your server as needed

Since now I'm just creating singleton and save the data into the server directly

BTW, Bob, Google just posted an article about that new Android Studio 2.0 emulator: android-developers.blogspot.com/2015/12/android-studio-20-preview-android.html

er, http://android-developers.blogspot.com/2015/12/...

okay thanks Mark

Great! I'll take a look.

Which one is most appropiate for sync list of data: Android Async vs OKHttp?

either should be fine

I tend to use OkHttp

Is there any pro cons?

I like OkHttp's API better

it also dovetails nicely with Retrofit and Picasso

I'm not sure if AndroidAsync has SPDY or HTTP/2 support

This is probably not a good question for a chat session, but I'll ask anyway: I'm still looking at Android architecture diagrams to develop a clear picture of what is in firmware and what gets pulled in from the SDK, particularly the Java libraries. Any tips? Pointers to docs?

Bob: you might try books on Android internals, like Karim Yaghmour's

Will try that

the only things in the "SDK" that become part of your APK are the support libraries

any Java class that doesn't begin with android.support. is only in the SDK in stub form, with the real implementation coming from firmware-supplied code, loaded into the zygote

where the zygote is the master SDK app process that all SDK apps get forked off of

now, if your concern is what happens directly in your process versus other processes, or what happens in Java code versus native callouts, that's another matter

books on the internals probably get into that somewhat, particularly on the IPC side

I'm interested with the size of the APK, so if we use the non-android.support one it will be less size in SDK?

Michael: any code you add to your app makes your app bigger, whether that code is yours or comes from a library

So if I'm targeting >15 better to use non-android.support?

That helps. I do have some understanding of the numerous "system services" and the Binder interfaces to them.

Sorry, I mean >=15

MichaelL: that is a controversial question

using the support libraries, at least to some extent, is nearly unavoidable

the less you use, the better ProGuard can strip out the unused stuff and minimize their impact

if you are really asking "is it better to not use AppCompatActivity?"... that's where the controversy comes in

I am not a fan of appcompat-v7

that's less an issue of size and more an issue of the way appcompat-v7 is implemented and concerns over long-term stability

however, I am in the minority in this opinion

which isn't the first unpopular opinion that I have held, nor will it be the last :-)

using appcompat-v7 and AppCompatActivity is the conventional choice today

I just happen to sneer in the general direction of convention :-)

thanks for the good and honest explanation, Mark :-)

Last question, I'm trying to make a preference settings

There is a AppCompatPreferenceActivity

that would be if you are using appcompat-v7 and AppCompatActivity

But read on many sources use the PreferenceScreen

a PreferenceActivity or PreferenceFragment uses a PreferenceScreen

I'm not aware of anyone using a PreferenceScreen directly, outside of a PreferenceActivity or PreferenceFragment

I'm not even sure that it is possible, though I've never really looked into it

I also want to try that one.. Thanks

that's a wrap for today's chat

the transcript will be posted to https://commonsware.com/office-hours/ shortly

the next chat is Saturday at 9am US Eastern

have a pleasant day!