Mtc spring 2014 best practices to develop for different android device classifications

Hasan Hosgel | ImmobilienScout24
Best Practices to develop for
different Android Device
Classifications

About me
• +HasanHosgel
@alosdev
alosdev
hosgel
CO-Organizer
Developer

ImmobilienScout24
Germany’s largest real estate listing company.
> 10 Mio. Monthly unique users
> 1.5 Mio. real estates
> 300 Mio. detail views
> 1500 Servers
~ 7.5 Mio. App downloads
> 3 Mio. Android
> 50% mobile traffic

Fragmentation
> 5000 Android Devices

Here comes the Nightmare
Image source:
http://www.flickr.com/photos/boogeyman13/4553188509/

Image source:
http://www.flickr.com/photos/boogeyman13/4553188509/
Here comes the Nightmare
For developers

Let’s build the fundament
Image source:
http://www.flickr.com/photos/hertenberger/1434191066/

Device Classification
Image source:
https://play.google.com/store/devices

Image source:
https://play.google.com/store/devices
http://www.htc.com

Image source:
http://www.sony.de/hub/google-tv

Image source:
https://developer.ford.com/

Open Automotive Alliance
Starting 2014 several companies plan to
bring Android platform to the cars.
• Audi
• GM
• Google
• Honda
• Hyundai
• Nvidia
http://www.openautoalliance.net/

Hard Work Ahead
Image source:
http://www.flickr.com/photos/16210667@N02/9172895225

Resource Folders
You can use several qualifiers in the
resource folders name for serving the
best matching resource.

Qualifiers
• Language (-en)
• Language & Region (-en-rUS)
• Smallest Width (–sw600dp)
• Screensize (-small, -normal, -large)
• Screen Orientation (-port, -land)
• Screen Pixel Densitiy (-hdpi, -xxhdpi,…)
• Platform Version (-v11, -v13)

Best Matching Resource Wins
1. res/values/strings.xml
2. res/values-en-rUS/strings.xml
3. res/values-large/strings.xml
4. res/values-sw600dp/strings.xml

Best Matching Resource Wins
1. res/values/strings.xml
2. res/values-en-rUS/strings.xml
3. res/values-large/strings.xml
4. res/values-sw600dp/strings.xml
The order of the qualifiers in the previous
slides gives the ranking, if two resources
have the same matching number of
qualifiers.

Image Resources
• Use the different qualifiers for the screen pixel
density (mdpi, hdpi, etc.)
• If you are forced to use text on images use
language and region (en, es-rUS, en-rUS, etc.)
• Better approach is to use 9-patch
drawables, which stretches automatically
depending on the content inside.
• You must provide different launcher icons for
Froyo, Honeycomb and above? Use the
platform version. (v4, v11, v14)

Classifications for Layouts
Platform version at least v13 (Honeycomb
MR2)

MR2)
project-folder/res/
layout/

MR2)
project-folder/res/
layout/  small phones

MR2)
project-folder/res/
layout-sw320dp/  other phones

MR2)
project-folder/res/
layout-sw600dp/  tablets 7”

MR2)
project-folder/res/
* You should also use the orientation qualifier

Platform version lower v11
project-folder/res/
layout/

project-folder/res/
layout/  phones

project-folder/res/
layout/  phones
layout-v11/  tablets 10”

project-folder/res/
layout/  phones
layout-v11/  tablets 10”
layout-v13/  small phones

Hint
The smallest width qualifier gets
automatically platform version ”-v13”
through the packager, for avoiding
problems with the number of matching
qualifiers.

How to Classify In Code
• Read configuration from the device

How to Classify In Code
• Read configuration from the device
• Smarter approach is to use boolean
resources

project-folder/res/values/layouts.xml
<resources>
</resources>

<resources>
<bool name="is_phone_other">false</bool>
<bool name="is_tablet_7">false</bool>
</resources>

<resources>
<bool name="is_phone_other">false</bool>
</resources>
Usage in code:
getResources().getBoolean(R.bool.is_phone_small)

Current Layout File Structure
project-folder/res/
layout/main.xml
layout-v11/main.xml
layout-v13/main.xml
layout-sw320dp/main.xml

project-folder/res/
layout/main.xml
layout-v11/main.xml
layout-v13/main.xml
Fixing one bug in the 10“ layout has to be done in two files.

project-folder/res/
layout/main.xml
layout-v11/main.xml
layout-v13/main.xml
Fixing one bug in the 10“ layout has to be done in two files.
 error prone

Resource Alias
Put your layout files in the default folder.
project-folder/res/
layout/main_phone_small.xml
layout/main_phone_other.xml
layout/main_tablet_7.xml
layout/main_tablet_10.xml

Create an item with the needed
classification in the previously defined
values folder.
project-folder/res/values-sw720dp/layouts.xml
<resources>
</resources>

values folder.
<resources>
<item name="main" >
</item>
</resources>

values folder.
<resources>
<item name="main" type="layout">
</item>
</resources>

values folder.
<resources>
<item name="main" type="layout">
@layout/main_tablet_10.xml
</item>
</resources>

Usage include
<LinearLayout … >
…
< />
…
</LinearLayout>

Usage include
<LinearLayout … >
…
<include />
…
</LinearLayout>

Usage include
<LinearLayout … >
…
<include layout="@layout/footer"/>
…
</LinearLayout>

Custom View
public class CustomView extends LinearLayout {
…
public CustomView(Context context, AttributeSet attrs) {
…
addView(createTextView(context, "label"), lp);
addView(createTextView(context, "desc"), lp);
if(getResources().getBoolean(R.bool.is_phone)){
setOrientation(VERTICAL);
} else {
setOrientation(HORIZONTAL);
}
}
…
}

Usage In Layout Files
<LinearLayout … >
…
<de.alosdev.CustomView
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
…
</LinearLayout>

Use <includes>
Create custom view

Custom XML Attribute
<resources>
<resources>

1. Add to root XML node
xmlns:app="http://schemas.android.com/apk/res-
auto"

1. Add to root XML node
xmlns:app="http://schemas.android.com/apk/res-
auto"
2. Usage in custom view
<de.alosdev.CustomView
android:id="@+id/customView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:label="label 1"
app:orientation="vertical"
app:value="value 1" />

public class CustomView extends LinearLayout {
static final int[] ORIENTATION = new int[] {
HORIZONTAL, VERTICAL };
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
…
TypedArray a =
context.obtainStyledAttributes(attrs, R.styleable.CustomView)
;
try {
setOrientation(ORIENTATION[
a.getInt(R.styleable.CustomView_orientation, 0)]);
} finally {
a.recycle();
}
}
…
}

If custom view has much more
business logic and need lifecycles
 Create a Fragment

Best Practices
You have already an application
 Remove orientation fixation and suppressing
of orientation change from manifest to avoid
long bug analyzing.
You start from the scratch
 Focus on main classification for faster time to
market
 But create an overall concept for better
modularization

If you support both orientations, save the instance
state while orientation changes for more
responsiveness
Especially for states, that need a long
computation for creation.
Make the state object Parcelable for faster
write & read and also to have a smaller memory
footprint

Developer Hints
• You can start an activity for result from a
fragment, so the response can be handled in the
fragment.
• If you want to register a special service on every
onCreate method of an activity give the
ActivityLivecycleCallbacks a try. You can register
them in the onCreate method of the application.
(minSDK -v14)

If you get a BadParcelableException with the cause
ClassNotFound-Exception, the source can be a
NullPointerException during the read or write of the
Parcelable. Exceptions are hidden during the parcel
process.

If you want to use “match_parent” or “wrap_content”
in a dimension alias, you should use “-1px” or “-2px”
project-folder/res/values/dimen.xml
<resources>
<dimen name="my_dimen>@dimen/match_parent</dimen>
<dimen name="match_parent">-1px</dimen>
<dimen name="wrap_content">-2px</dimen>
</resources>
project-folder/res/values-sw600dp/layout.xml
<resources>
<dimen name="my_dimen>300dp</dimen>
</resources>

Listener Hell
If you have to many listeners or you think the
programming model is old school like the “goto
statements”. Give message/ event/ service bus
a try. For Android:
• Otto from Square
• EventBus from greenrobot
See also: Callbacks as our Generations' Go To
Statement

Custom Theme & Style
Android Ui Utils

Mission Accomplished?
Image source:
http://www.flickr.com/photos/ianaberle/5729561934/

Mission Accomplished
Image source:
http://www.flickr.com/photos/ianaberle/5729561934/

Q & A
Image source:
http://www.flickr.com/photos/21496790@N06/5065834411/

www.immobilienscout24.dewww.immobilienscout24.de
Thanks for your attention!
Contact:
+HasanHosgel
@alosdev
alosdev
Best Practices to develop for different Android Device Classifications
https://github.com/alosdev/multidevice-nightmare-demo
http://www.slideshare.net/hosgel/mtc-spring-2014-best-practices-to-develop-for-different-
android-device-classifications

Mtc spring 2014 best practices to develop for different android device classifications

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