Transcript

Android UI, and Networking

Can do most networking on Android

Bluetooth only on 2.0,

Not supported with version 1.6

Bruce Scharlau, University of Aberdeen, 2009

Android has many components

Bluetooth and USB drivers now gone from kernelXMPP 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

Set value of inflated objectSet value of inflated object

INCOMPLETE CODEINCOMPLETE CODE

New view items and attached to xml valuesNew view items and attached to xml values

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

Bruce Scharlau, University of Aberdeen, 2009

Activity is one thing you can do

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

Bruce Scharlau, University of Aberdeen, 2009

Log output for debugging, etc

Simple method to call URL and return value

Might need robust calls to network

Put heavy lifting work in HTTPRequestHelper so accessible to other classes

Handler waits for message and then returns

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


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