Android dev tips

1. Android Dev Tips
Kanda Runapongsa Saikaew

2. Agenda
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Love Relative Layout
Use Hierarchy Viewer
Use Eclipse Effectively
Use LogCat
Publish Application

3. 1. Love Relative Layout
• Most of the tutorials use LinearLayout, but you will find
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that RelativeLayout is truly useful
A common example is the abuse of LinearLayout, which
leads to a proliferation of views in the view hierarchy
Every view, or worse every layout manager, you add to
your application comes at a cost: initialization, layout
and drawing become slower

4. Use LinearLayout

5. Use RelativeLayout

6. 2. Use Hierarchy Viewer
• The Android SDK tools include a tool called Hierarchy
Viewer that allows you to analyze your layout while your
application is running
• Hierarchy Viewer works by allowing you to select running
processes on a connected device or emulator, then display
the layout tree
• The traffic lights on each block represent its Measure,
Layout and Draw performance, helping you identify potential
issues.

7. Using HierarchyViewer
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The hierarchyviewer tool is available in <sdk>/tools/
When opened, the Hierarchy Viewer shows a list of
available devices and its running components

8. Using Hierarchy Viewer
• Click Load View Hierarchy to view the
layout hierarchy of the selected component

9. Using Hierarchy Viewer
- A small bitmap image on the left
- Two stacked items of text on the right

10. Using LinearLayout

11. Using LinearLayout
• There is a 3-level hierarchy with some
problems laying out the text items
• The timings for rendering a complete list
item using this layout are
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Measure: 0.977ms
Layout: 0.167ms
Draw: 2.717ms

12. Using RelativeLayout

13. Using RelativeLayout
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Because the layout performance above slows down due to
a nested LinearLayout
• The performance might improve by flattening the layout—
make the layout shallow and wide, rather than narrow and
deep
• Now rendering a list item takes
• Measure: 0.598ms
• Layout: 0.110ms
• Draw: 2.146ms

14. 3. Use Eclipse Effectively
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You should try to keep your hands on
keyboard
The less you touch the mouse, the more
code you can write
I am trying to keep the mouse laying still and
control the IDE completely using keyboard.

15. Eclipse Short Cut Keys
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Ctrl + D
Ctrl + 1
Ctrl + Shift + O
Ctrl + Shift + F
Ctrl + Shift + L
Delete row
Activates the quick fix
Organize imports
Format codes
Shows you a list of your
currently defined
shortcut keys

16. 4. Use LogCat
• It can be difficult in Android to figure out
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“what went wrong”.
LogCat will show cause of the problems.
o
o
Error message with red string.
Problems that cause by …. (something) with line of
that code.

17. How to Use LogCat
• To use LogCat, first import android.util.Log
into your project
• Now you can call the static class Log from
your project to start logging
• Logcat has different levels of logging

18. Different Levels of Logging
V — Verbose (lowest priority)
D — Debug
I — Info
W — Warning
E — Error
F — Fatal
S — Silent (highest priority, on which nothing is ever
printed)

19. Setting Different Colors for Different Levels
• Go to Preferences > LogCat > Colors

20. Example of Using Log Class

21. How to View LogCat
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Open LogCat view by clicking the LogCat icon at the
bottom right corner (1 in the figure)
Filter LogCat level (2 in the figure)
Search for some keyword (3 in the figure)

22. 5. Publish Application
• Prepare the application for release
• Release the application to users

23. Configure Your Application for Release
• Choose a good package
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The package name cannot start with com.example
• Turn off logging and debugging
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Remove Log calls
Remove android:debuggable attribute from your
manifest file
Remove all Debug tracing calls such as
startMethodTracing()

24. Configure Your Application for Release
• Clean up your directory
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Review the contents of your jni/, lib/, and src/ directories
• The jni/ directory should contain only source files
associated with the Android NDK, such as .c, .cpp, .h,
and .mk files
• The lib/ directory should contain only third-party library
files or private library files, including prebuilt shared and
static libraries
• The src/ directory should not contain any .jar files.

25. Configure Your Application for Release
• Review and update your manifest settings
• <uses-permission> element
• You should specify only those permissions that are
relevant and required for application
• android:icon and android:label attributes
• You must specify values for these attributes, which are
located in the <application> element
• android:versionCode and android:versionName attributes.
• We recommend that you specify values for these
attributes

26. Configure Your Application for Release
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Address compatibility issues
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Add support for multiple screen configurations.
Optimize your application for Android tablet devices.
• If your application is designed for devices older than
Android 3.0, make it compatible with Android 3.0 devices
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Consider using the Support Library.
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If your application is designed for devices running Android 3.x,
make your application compatible with older versions of Android

27. Support Different Devices
• Support different languages
• Support different screens
• Different layouts
• Different bitmaps
• Different text sizes

28. Support Different Languages
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Create the resource subdirectories and string resource
files
Example
MyProject/
res/
values/
strings.xml
values-es/
strings.xml

29. Support Different Languages
English (default locale), /values/strings.xml:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="title">My Application</string>
<string name="hello_world">Hello World!</string>
</resources>
Spanish, /values-es/strings.xml:
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="title">Mi Aplicación</string>
<string name="hello_world">Hola Mundo!</string>
</resources>

30. Support Different Screens
• Android categorizes device screens using two
general properties: size and density
• There are four generalized sizes: small,
normal, large, xlarge
• Four generalized densities: low (ldpi), medium
(mdpi), high (hdpi), extra high (xhdpi)

31. Support Different Layouts
MyProject/
res/
layout/
main.xml
# default (portrait)
layout-land/
# landscape
main.xml
layout-large/
# large (portrait)
main.xml
layout-large-land/ # large landscape
main.xml

32. Support Different Bitmaps
• To generate these images, you should start with your raw resource
in vector format and generate the images for each density using
the following size scale:
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xhdpi: 2.0
hdpi: 1.5
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mdpi: 1.0 (baseline)
ldpi: 0.75
• This means that if you generate a 200x200 image for xhdpi
devices, you should generate the same resource in 150x150 for
hdpi, 100x100 for mdpi, and 75x75 for ldpi devices.

33. Support Different Bitmaps
Then, place the files in the appropriate drawable resource directory:
MyProject/
res/
drawable-xhdpi/
awesomeimage.png
drawable-hdpi/
awesomeimage.png
drawable-mdpi/
awesomeimage.png
Any time you reference @drawable/awesomeimage, the system selects the
appropriate bitmap based on the screen's density.

34. Support Different Text Sizes
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You should use the resource folders such as
values-ldpi
values-mdpi
values-hdpi
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Write the text size in 'dimensions.xml' file for each range
Sample dimensions.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<dimen name="textsize">15sp</dimen>
</resources>
•
In Java code, textView.setTextSize(getResources().getDimension(R.dimen.textsize));

35. What to Test
• Change in orientation
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Is the screen re-drawn correctly?
Does the application maintain its state?
• Change in configuration
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A situation that is more general than a change in
orientation is a change in the device's configuration,
such as a change in the availability of a keyboard or
a change in system language

36. What to Test
• Battery Life
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You need to write your application to minimize
battery usage, you need to test its battery
performance, and you need to test the methods that
manage battery usage.
Techniques for minimizing battery usage were
presented at the 2010 Google I/O conference in the
presentation Coding for Life -- Battery Life, That Is.

37. What to Test
• Dependence on external resources
• If your application depends on network access,
SMS, Bluetooth, or GPS, then you should test what
happens when the resource or resources are not
available
• For example, if your application uses the network, it
can notify the user if access is unavailable, or
disable network-related features, or do both

38. References
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http://stackoverflow.com/questions/2961049/effective-android-programmingtechniques
http://www.curious-creature.org/2009/02/22/android-layout-tricks-1/
http://www.curious-creature.org/2012/12/01/android-performance-case-study/
http://developer.android.com/training/improving-layouts/optimizing-layout.html
http://eclipse.dzone.com/news/effective-eclipse-shortcut-key
http://developer.android.com/tools/testing/what_to_test.html
http://developer.android.com/tools/publishing/preparing.html
http://stackoverflow.com/questions/9494037/how-to-set-text-size-of-textviewdynamically-for-diffrent-screens
http://developer.android.com/training/basics/supporting-devices/screens.html

39. Thank you
Kanda Runapongsa Saikaew
• Khon Kaen University, Thailand
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Assistant Professor of Department of Computer Engineering
Associate Director for Administration of Computer Center
krunapon@kku.ac.th
Twitter: @krunapon
G+: https://plus.google.com/u/0/118244887738724224199