Android App Development Beyond The HelloWorld App

Cape Town Android MeetupJoseph Kandi

Peruzal Android App Development Training Team

www.peruzal.co.za

Take Aways

!Android Development Environment Android Application Components Threads in Android Designing Android UIs in XML Using Intents Performing Web Service Calls

Android Development Environment

• Java

• Eclipse | Android Studio

• Android SDK

Java Skill Level

• Variables

• Operators

• String

• Loops

• Methods

• Class

• Static

• Inheritance

• Packages and Import

• Access Levels

• Constants

• Interface

• Inheritance

• Abstract

• Generics

• Casting

• Threads

• Enum

• Exception Handling

• Boxing and UnBoxing

Android and Java

Android Software Stack

Custom Linux 2.6 kernel

SQLite, WebKit, SSL, OpenGL ES, Media

Framework

Content Providers, Activity Manager, Window Manager, View

System, Notification System, Telephony Home, Contacts, Browser,

Yamba

Inside Android

System partition

Use command adb shell to logon to the device

Note the permissions on the folders

sdcard

Android Versions and API Level

Get Java

http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html

Eclipse

http://developer.android.com/sdk/index.html

Download from this link

Android Studio

Still buggy, not ideal for beginners to Android development

Download from here

Building Blocks

Activities Services Content Providers Broadcast Receivers Application

Activity

An activity is a single, focused thing that the user can do.

Activity Life Cycle

Activity Class

Called the activity is first created

Called when the activity is becoming visible to the user

Called after the activity has been stopped, prior to it being

started again

Called when the activity will start interacting with the user

Called when the system is about to start resuming a

previous activity Called when activity is no longer visible

Final call before the activity is destroyed

Intents

Messages sent among the major building blocks. They trigger an action to start up, tell a service to start or stop, or simple

broadcast

Services

Services run in the background and don’t have a user interface components

Content Providers

Interfaces for sharing data

Broadcast Receivers

Android implementation of publish/subscribe mechanism or the Observer pattern

Application Context

Refers to the application environment and the process within which all the components are running !

Used to share data between components

Context.getApplicationContext

Activity.getApplication

Android User Interface

Java - done in code XML - declarative

Views

Android organizes its UI into layout and views

Write the xml

Load the XML Resource

Layouts

Example Linear Layout

Also called match_parent

Either

Relative Example

Creating a New Project

• Walkthrough, create a new project

Choose New Project

The name of the appProject Name - NB No spaces allowed

Package name, usually reverse dns of your company name

Minimum supported SDK the app will run on

The version of Android we are

building forDoes not do anything,

ignore

Create an initial activity

Customize the launcher

Preview of the launch icon on different screen resolutions

Path for the image used as a launch icon on the home screen

Choose Activity Type

Choose different activity types

Choose “Blank Activity” here

Choose Main Activity Name

Leave it as MainActivity for now, in future we will change it

The xml file defining the user interface for our

activity

Leave as is

Project Structure

Main activity created during project

setup

Resource folders go under “res” folder

xml layout file defining the screen for

the app

Explains what application consists, the main building

blocks, permissions

AndroidMainfest.xml

Package name for the application

Android SDK

Activity declaration

Main activity action

Intent Category of the action

Layout xmlLive preview

xml defining the UI

File lives under “layout” resource folder

Layout container

xml properties

View component

Main Activity xml file

Java file

Extends Activity class

Using the class R to point to the layout

R file | Auto-generated

R.layout.activity_main, referring to the file under /layout/activity_main.xml

strings.xml

Key used to retrieve the string

Value

AVD | Android Virtual Device Launch AVD manager

Launch AVD manager

AVD ManagerAVD images

Available devices, need at least one to test the app

Add a new AVD

Create a New AVD

Choose name, no spaces allowed

Choose device specifications

Camera support

Amount of RAM

Improves speed of the emulator

Android SDK version

User Interface and Controls

• Project Overview

Project Overview

Yamba App Context

TwitterService

StatusActivity

poststatusupdate

1

Status Activity

Timeline Activity

Action Bar | Menu

Preferences