Getting Dirty with Android

Getting Dirty With Android

Brent Edwards
Senior Consultant with Magenic
BrentE@magenic.com
@brentledwards
brentedwards.net

What We Will Cover
Menus
Layout
Styles
Lifecycle Management
AsyncTask
All while building a sample app

Assumptions
Basic understanding of…
Android
Activities and Intents
Resources

Menus
3 Flavors
Options Menu
Primary Menu Type
Menu Button Pressed
First 5-6 Options -> Icon Menu
When 7+ options, Option 6+ -> Expanded Menu
Context Menu
Long Press
Sub Menu

Menus
Define menus in XML
res/menu/
Inflate the XML resource in code

Menus
[Demo]

Layout

Layout
Defines what the UI looks like
Where views are placed
How big views are
How views flow
Made up of nested views

Layout
2 Ways to define layout
XML
Provides most flexibility
Better separation of UI from logic
Easier to visualize
Programmatically
Can be more difficult
Best when coupled with XML and LayoutInflater

Layout - XML
Valid XML file
Each node maps to a view instance
Attributes set properties on the view
Layout File Convention
Have .xml extension
Named with all lowercase
Placed in res/layout/ folder

Layout
Most Useful Layout Objects
LinearLayout
RelativeLayout

Layout - LinearLayout
Views are stacked [horizontally|vertically]

Layout - LinearLayout
Why it is so useful
Simple to use
Easy to understand at a glance
Can leverage weight for children to scale proportionally

LinearLayout
[Demo]

Layout - RelativeLayout
Views specify their position relative to parent, other views or both

Layout - RelativeLayout
Why it is so useful
Very versatile
Scales very well
Handles rotation easily

RelativeLayout
[Demo]

Styles

Styles
Specifies look and format for views
Separates design from content
Collection of properties
Font Size
Font Color
Background Color
Padding
Margin
Much more

Styles
Adds consistency to UI
Similar to CSS

Styles
Styles file convention
Have .xml extension
style.xml
Placed in res/values/

Style
[Demo]

Applications have a lifecycle
Essentially Three States
Active / Running
Paused
Stopped

Stopped Activities can be killed
Then recreated when brought to front
Activities with state need to be serialized
onPause()
onSaveInstanceState()

[Demo]

AsyncTask

AsyncTask
Tasks run asynchronously
Doesn’t freeze UI
Good for long running tasks
Web requests

AsyncTask
Defined by 3 generic types
Params
Progress
Result

AsyncTask
4 Steps
onPreExecute
Executes on UI thread
doInBackground
Executes the actual task on background thread
onProgressUpdate
Optionally updates user on progress on UI thread
onPostExecute
Executes on UI thread

AsyncTask
Rules
Task must be created in UI thread
execute must be invoked from UI thread
Tasks can only be executed once
Don’t call onPreExecute, onPostExecute, doInBackground or onProgressUpdate manually

AsyncTask
[Demo]

Dialogs

Dialogs
Types
AlertDialog
ProgressDialog
DatePickerDialog
TimePickerDialog
Override Dialog class to create Custom Dialogs

Dialogs
To show a Dialog
Simple way
More complex way
Override onCreateDialog(int)
Call showDialog(int)

Dialogs
[Demo]

Valuable Links
Fundamentals
http://developer.android.com/guide/topics/fundamentals.html
Menus
http://developer.android.com/guide/topics/ui/menus.html
Layout
http://developer.android.com/guide/topics/ui/declaring-layout.html
Styles
http://developer.android.com/guide/topics/ui/themes.html
AsyncTask
http://developer.android.com/reference/android/os/AsyncTask.html
Dialogs
http://developer.android.com/guide/topics/ui/dialogs.html

Questions?

Brent Edwards
Senior Consultant with Magenic
BrentE@magenic.com
@brentledwards
brentedwards.net

Getting Dirty with Android

by Brent Edwards on Oct 09, 2010

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Getting Dirty with Android — Presentation Transcript