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 kernel 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 Set value of inflated object INCOMPLETE CODE New view items and attached to xml values

Android emulator runs as ‘localhost’, ie ‘loopback’ Emulator is at 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