This document discusses menus, frame layouts, and lists in Android mobile app development. It covers creating custom menus as resources, handling menu clicks, and displaying toasts. It also explains how to use frame layouts to overlay views and toggle visibility. Finally, it discusses using adapters to connect lists to data sources and format each list item view.

1. HIT3328 / HIT8328 Software Development for
Mobile Devices
Dr. Rajesh Vasa, 2011
1
Twitter: @rvasa
Blog: http://rvasa.blogspot.com
Lecture 06
Menus and Lists

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Lecture Overview
•Working with Menus
•Using Frame Layout
•Adapters and Working with Simple Lists

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Menus
•Android offers a ‘Menu’ button, iOS does not
•Menus’ can be customised per activity
Menus have a label and an icon
Icon is strongly recommended by
the Android UI guidelines
Menu
Icons at different resolutions
should be provided (ideally)

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Creating a Menu
Name App (from Lecture
5)
Menus are defined as a
resource
We can use icons provided by
Android SDK (recommended)
We can use icons provided by
Android SDK (recommended)

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Menus are Resources
Convention is to place it
in ‘menu’ folder

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Wiring up a Menu to Show
Call back method that we have to write
Resource Identifier
XML Resource file is converted (inflated)
into a Menu object that will be rendered
(shown) on screen
XML Resource file is converted (inflated)
into a Menu object that will be rendered
(shown) on screen

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Handling Menu Click
Call back method that we have to write

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Toasting a Message
•There is often a need to show a message
for a short period and then fade on mobile
devices
•Android offers this via the Toast utility

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Toasting a Message
On Click
Message
displayed for a
second

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Creating a Toast
Duration can be customised
Android offers Toast.LENGTH_LONG,
Toast.LENGTH_SHORT as built in defaults
Duration can be customised
Android offers Toast.LENGTH_LONG,
Toast.LENGTH_SHORT as built in defaults

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Lecture Roadmap - Where are
we?
•Working with Menus
•Using Frame Layout
•Adapters and Working with Simple Lists

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Frame Layout Offers Overlays
•We often need a way to overlay multiple
views (or layouts) on top of each other
•Often with variation in transparency
•Frame Layout offers us this feature
•Frame Layout is also used to help create
Tab Panes in Android

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Simple Frame Layout (Light
Bulb)
Button is placed on top of Image View
n / Off Images are also placed on top of each othe

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Frame Layout - Code
2 Image Views and 1 Button in the same layout

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Frame Layout - Code
We control visibility explicitlyWe control visibility explicitly

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Light Bulb Logic
We flip the visibility of the images
Method is triggered onClickMethod is triggered onClick

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Lecture Roadmap - Where are
we?
•Working with Menus
•Using Frame Layout
•Adapters and Working with Simple
Lists

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A Simple List App.
Displays Latitude and Longitude of a location

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Constituents of a List based
screen
ListView
Text Views

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Lists get data via an Adapter
ListView
Data Source
Adapter

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Adapter Formats Data for
Display
ListView
Data Source
Adapter
Data is formatted for
display via customised
layout attached to the
Adapter
Data is formatted for
display via customised
layout attached to the
Adapter

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List Views are very flexible
We specify the
layout for each line
item of a list
Layout can be provided
as a resource file (XML)

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Adapter Feeds data to List
View
ListView
Data Source
Adapter
Data Source feeds data
to the Adapter for
formatting
Data Source feeds data
to the Adapter for
formatting

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Adapter Offers Separation of
Concerns
ListView
Data Source
Adapter
Data Source can be an
array, collection object,
external database, or an
external server
Data Source can be an
array, collection object,
external database, or an
external server

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Simple List App.
ListView
Data Source
Adapter
Domain Model:
HashMap (Cities, Location)
(Cities names)
(Simple Item
Layout)

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Domain Model
Ideally, you read an external resource
(Above data is hard-coded to illustrate concept)

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Wiring up Data - Adapter -
ListView
Activity extends ListActivity
We are using an Array Adapter
(others are available / you can
provide your own)

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Wiring up Data - Adapter -
ListView
We are using SDK provided layout style
(we can also write our own as an Layout XML)

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Wiring up Data - Adapter -
ListView
We are setting the data source to use

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Wiring up Data - Adapter -
ListView
Tell the List View to display from adapter

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Wiring up Data - Adapter -
ListView
Only one ListView can receive
data via the default
setListAdapter in an Activity

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Activity Layout
ListView that will receive data
provided via setListAdapter

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Activity Layout
ListView that will receive data
provided via setListAdapter
Special
built-in
identifier
Special
built-in
identifier

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Handling List Click Event
This call back is provided by the
parent (List Activity) class -- we
override it
This call back is provided by the
parent (List Activity) class -- we
override it

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But, what about complex lists?
Key concepts are the
same
We will cover it later in
depth
(if you are curious, look at examples
online)

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Lecture Summary
•Working with Menus
•Using Frame Layout
•Adapters and Working with Simple Lists