Droidcon it 2014 best practices to develop for different android device classifications

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Best Practices to develop for
different Android Device Classifications

Droidcon | Turin| 07.02.2014 | Hasan Hosgel

About me

+HasanHosgel
Twitter: @alosdev
Github:
alosdev
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Android in Berlin
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developer @
ImmobilienScout24

Droidcon IT 2014 | Develop for different device classifications | Hasan Hosgel

About 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


Fragmentation

> 5000 Android Devices


Here comes The Nightmare

Image source:
http://www.flickr.com/photos/boogeyman13/4553188509/

Here comes The Nightmare

For developers
Image source:
http://www.flickr.com/photos/boogeyman13/4553188509/

Let’s build the fundament

Image source:
http://www.flickr.com/photos/hertenberger/1434191066/

Device Classification

Images sources:
https://play.google.com/store/devices



Images sources:
https://play.google.com/store/devices
http://www.htc.com/de/



Images sources:
http://www.sony.de/hub/google-tv



Images Sources
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/


Wearables


Glass


Hard Work Ahead


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, -xhdpi, -xxhdpi)
● Platform Version (-v11, -v13)


Best Matching Resources Win

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 Resources Win

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.


Images 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/

 small phones

layout-sw320dp/

 other phones



MR2)
project-folder/res/

layout/

 small phones

layout-sw320dp/

 other phones

layout-sw600dp/

 tablets 7”



MR2)
project-folder/res/

layout/

 small phones

layout-sw320dp/

 other phones

layout-sw600dp/

 tablets 7”

layout-sw720dp/

 tablets 10”

* You should also use the orientation qualifier


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

 phones

layout-sw320dp/

 other phones

layout-sw600dp/

 tablets 7”

layout-sw720dp/

 tablets 10”


project-folder/res/
layout/

 phones

layout-v11/

 tablets 10”

layout-sw320dp/

 other phones

layout-sw600dp/

 tablets 7”

layout-sw720dp/

 tablets 10”


project-folder/res/
layout/

 phones

layout-v11/

 tablets 10”

layout-v13/

 small phones

layout-sw320dp/

 other phones

layout-sw600dp/

 tablets 7”

layout-sw720dp/

 tablets 10”


Hint

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


Howto Classify In Code

• Read configuration from the device


Howto 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


Resource Alias

2. Create an item with the needed
classification in the previously defined values
folder.

project-folder/res/valuessw720dp/layouts.xml
<resources>

</resources>

Resource Alias

folder.

<resources>

<item

>
</item>

</resources>

Resource Alias

folder.

<resources>

<item name="main"

>
</item>

</resources>

Resource Alias

folder.

<resources>

<item name="main" type="layout">
</item>
</resources>

Resource Alias

folder.

<resources>

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

Sample Screen


Sample Screen

Use <includes>

Usage Includes

<LinearLayout … >
…
…
</LinearLayout>


Usage Includes

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

/>


Usage Includes

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


Sample Screen

Create custom view

Use <includes>

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 CustomView in layout file

<LinearLayout … >
…

…
</LinearLayout>


Usage CustomView in layout file

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


Custom XML Attribute
<resources>
<declare-styleable

>

</declare-styleable>
<resources>


Usage in layout resource

1. Add to root XML node
xmlns:app="http://schemas.android.com/apk/resauto"
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" />


Usage in code

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


Code


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

Best Practices

● 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
“-1dp” or “-2dp”
project-folder/res/values/dimen.xml

<resources>
<dimen name="my_dimen>@dimen/match_parent</dimen>
<dimen name="match_parent">-1dp</dimen>
<dimen name="wrap_content">-2dp</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


ActionBar Style Generator


Holo Color Generator


Mission Accomplished ?

http://www.flickr.com/photos/ianaberle/5729561934/

Mission Accomplished

http://www.flickr.com/photos/ianaberle/5729561934/

Q&A

Page 85
Source: http://www.flickr.com/photos/21496790@N06/5065834411/

www.immobilienscout24.de

Thanks for your attention!
Contact:
+HasanHosgel
Twitter: @alosdev
Github: alosdev

Best Practices to develop for different Android Device Classifications
https://github.com/alosdev/multidevice-nightmare-demo
http://www.slideshare.net/hosgel/droidcon-it-2014-best-practices-to-develop-fordifferent-android-device-classifications

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