Transcript Lecture 9 - Bhecker.com

Android UI, and Networking
Can do most networking on
Android
Bluetooth only on 2.0,
Not supported with version 1.6
Android has many components
Bluetooth and USB drivers now gone from kernel
Bruce Scharlau, University of Aberdeen, 2009
XMPP gone
from application framework
All layouts are hierarchical
All
screens
are
derived
from view
Hierarchical views can include
similar groups
Children do as told in Android
TextView is child of parent viewgroup and fills,
or wraps content
There are many types of
controls in Android
Lists can be handled via adapters
and filled from xml file of values
Table layout allows for just that
with data
Use the hierarchy viewer tool to
optimize and debug interface
Views are tied to activities
(screens) in Android
One class per
activity, and
screen, which
may be done
as xml file
One layout per activity (class)
main.xml goes with AuctionStart
list.xml goes with ListItems
hit_server.xml goes
with HitServer
Xml layout file details components
Hierarchy of views
as noted earlier
Xml layout inflated in onCreate
New view items and attached to
xml values
Set value of inflated object
INCOMPLETE CODE
Android emulator runs as
‘localhost’, ie ‘loopback’
Emulator is at 127.0.0.1 so
need to call service at IP
address of service to test
network apps on developer
machine
Activity is one thing you can do
Bruce Scharlau, University of Aberdeen, 2009
Apps move through states
during lifecycle
onPause is last state
to preserve state and
cleanup before app
possibly destroyed
Handler class provides access
to running thread for main UI
Handler has Looper which
contains MessageQueue that
can be called and return
objects to UI thread
Handler puts thread response
into UI thread
Method returns string from network
Log output for debugging, etc
Bruce Scharlau,
University
of Aberdeen,
Simple
method
to call
URL2009
and return value
Might need robust calls to network
Handler waits for message
and then returns
Put heavy lifting work in HTTPRequestHelper
so accessible to other classes
Parse xml response and
populate Java bean instance
Bruce Scharlau, University of Aberdeen, 2009
Add permissions to manifest for
connection and network
Bruce Scharlau, University of Aberdeen, 2009
End of Lecture