A new version of the Architecture Components was released
today.
Well, OK, actually, three versions of the Architecture Components were
released today.
Though, in truth, it’s more like the Architecture Components have undergone
mitosis, with different component cells going their own way with respect to version
numbers and versioning systems.
Confused yet?
“Iceberg, Right Ahead!”
When we depend upon artifacts like com.android.support:support-v4 or
android.arch.persistence.room:runtime:1.0.0-alpha9-1, we perceive the
artifacts that show up in the dependencies roster in our Gradle build files.
However, like an iceberg, we are only seeing a fraction of the actual artifacts,
with the rest being pulled in via transitive dependencies.
And, when it comes to Android libraries from Google, those transitive dependencies
frequently are undocumented.
In general, that lack of documentation isn’t usually a problem. Sometimes it is,
and it is the source of some of the confusion around today’s release(s).
Specifically, when we depend upon android.arch.lifecycle:runtime,
there is a transitive dependency on android.arch.lifecycle:common. And
android.arch.lifecycle:common is undocumented.
So, What Went to 1.0.0?
The 1.0.0 Alpha 9-1 release notes state:
This is a major release where core lifecycle artifacts (runtime, common) and arch core (common) reach to stable version 1.0.0.
Exactly what reached “stable version 1.0.0” is undocumented, because the
quoted passage refers to undocumented things.
Compounding the problem is that
the documentation
cites an artifact version (android.arch.lifecycle:runtime:1.0.0-alpha9-1) that
does not exist, or at least is not being served by Google’s Maven repository.
(UPDATE 2017-09-15: fixed now, points to android.arch.lifecycle:runtime:1.0.0)
The 26.1.0 support libraries (e.g., com.android.support:support-compat:26.1.0)
depend upon android.arch.lifecycle:runtime:1.0.0, which in turn depends
upon the undocumented android.arch.lifecycle:common:1.0.0. So, those two
artifacts are at a stable 1.0.0 version.
Near as I can tell, nothing else of the “classic” Architecture Components
are at a 1.0.0 just yet. The artifacts that I tested all resolved to
a 1.0.0-alpha9-1 version. So, for example,
android.arch.lifecycle:extensions:1.0.0-alpha9-1 depends upon
android.arch.lifecycle:runtime:1.0.0.
FWIW, there are also other undocumented artifacts, with disparate versions:
-
android.arch.core:common, where the current version seems to be 1.0.0
-
android.arch.core:runtime, where the current version seems to be 1.0.0-alpha9-1
These appear to be what the quoted passage refers to as “arch core”.
Enter Paging
The Architecture Components now have a new component:
Paging.
The release notes state that “Paging is released as alpha1 and will have its own release cycle.”
Indeed, android.arch.paging:runtime:1.0.0-alpha1 does exist. It, in turn,
depends upon an undocumented android.arch.paging:common:1.0.0-alpha1. But, at
least those versions are in sync.
However, 1.0.0-alpha1 is not 1.0.0-alpha9, nor is it 1.0.0, so we have
three different version numbers within the same family of artifacts.
FWIW, android.arch.paging:runtime:1.0.0-alpha1 and
android.arch.paging:common:1.0.0-alpha1 depend upon a mishmash
of 1.0.0 and 1.0.0-alpha9-1 dependencies from other libraries.
In the fullness of time, this will all get cleared up, in all likelihood. For
now, it’s more than a bit confusing, requiring rummaging through POM files to
see what is going on.
—Sep 14, 2017
Subscribers now have
access to an update to Android’s Architecture Components,
known as Version 0.3, in PDF, EPUB, and MOBI/Kindle formats. Just log into
your Warescription page and download
away, or set up an account and subscribe!
This is a small update, bringing in two new chapters on RxJava in Room
and packaging a Room database with your app. It also covers the current 1.0.0-alpha9 version
of the Architecture Components, fixes a variety of errata, and makes other
small improvements.
The next update to this book should come in early November or thereabouts.
—Sep 13, 2017
Subscribers now have
access to Version 0.3 of GraphQL and Android, in PDF, EPUB, and
MOBI/Kindle formats. Just log into
your Warescription page and download
away, or set up an account and subscribe!
In this update, there are… call it “one and a half” new chapters:
-
One on paginated GraphQL queries, using the Relay connection pattern, and how
we can consume them in Android
-
One partial chapter on advanced Apollo-Android techniques
In addition:
-
All URLs in the samples and prose now point to 0.3/ instead of 0.2/
in their paths
-
The samples using Apollo-Android now use 0.4.0 of that library
-
There are a few errata fixes and the like.
The next update to this book should be out in 1-2 months.
—Aug 30, 2017
One of the reasons why I keep close tabs on Stack Overflow is that, every now
and then, I’m reminded of a technique that I should be promoting more.
Today’s example of this comes from this question,
where a developer inheriting an existing Android Studio project questioned
why the project had a res/values/drawables.xml file that contains
a bunch of <item> elements:
<resources xmlns:android="http://schemas.android.com/apk/res/android">
<item name="ic_menu_camera" type="drawable">@android:drawable/ic_menu_camera</item>
<item name="ic_menu_gallery" type="drawable">@android:drawable/ic_menu_gallery</item>
<item name="ic_menu_slideshow" type="drawable">@android:drawable/ic_menu_slideshow</item>
<item name="ic_menu_manage" type="drawable">@android:drawable/ic_menu_manage</item>
<item name="ic_menu_share" type="drawable">@android:drawable/ic_menu_share</item>
<item name="ic_menu_send" type="drawable">@android:drawable/ic_menu_send</item>
</resources>
What the original developer did was set up project aliases for platform resources.
There are lots of resources available in the Android SDK. You are welcome to
refer to them directly if you want, such as @android:string/ok or
android.R.color.black.
However, platform resources have two key problems:
-
They tend to be very specific. android.R.color.black is a color resource
that resolves to black. It should always be black.
-
They might vary by Android version or even device manufacturer build. Some
manufacturer, or even Google itself, might decide that orange is the new black
and have android.R.color.black resolve to some shade of orange.
Ideally, you add a bit of indirection here, so that all of your Java code
and other resources that today might use platform resources could switch
tomorrow to some other implementation of those resources, without having
to change all of the references to the resources.
Sometimes, we do this via styles and themes. However, that gets confusing,
can be overkill, and does not necessarily cover all scenarios.
Resource aliases are another approach, the one taken by the original developer
of the code from the Stack Overflow question. <item> elements, with
type pointing to the type of resource, gives us indirection. With the
above XML in a project, the project code and other resources can refer
to R.drawable.ic_menu_share and such. Right now, the implementations of
those drawables happen to be platform resources, by means of the <item>
elements. However, later on, you could get rid of the <item> elements and
add custom drawables as replacements. Nothing that refers to the resource
needs to change, courtesy of the indirection.
Even in cases where you do not think that you will need to switch to a
custom resource, using this sort of indirection technique lets you
use logical resource names (e.g., R.color.divider instead of
android.R.color.black, to make it easier for you to switch to
android.R.color.holo_orange_dark later on without other code changes).
Again, styles and themes may supplant the need
for a lot of these aliases, but not everything belongs in a style resource.
—Aug 22, 2017
Subscribers now have
access to an update to Android’s Architecture Components,
known as Version 0.2, in PDF, EPUB, and MOBI/Kindle formats. Just log into
your Warescription page and download
away, or set up an account and subscribe!
This is a small update, bringing in two new chapters on M:N relations in Room
and LiveData transformations. It also covers the current 1.0.0-alpha8 version
of the Architecture Components, fixes a variety of errata, and makes other
small improvements.
The next update to this book should come in late September or thereabouts.
—Aug 14, 2017
