Developing Android ApplicationsIntroduction to Software Engineering – Fall 2015

Updated 7 October 2015

Android Lab 1Introduction to Android

Class Assignment: Simple Android Calculator

2

Class Plan

• Introduction

• Android Studio• Installation Guide

• Project Setup

• Android Simulation Setup

• Interface Setup

• Basic Concepts

• Lab Assignment: Calculator

3

Introduction

4

What’s Android

• The world's most popular mobile platform

• Powerful development framework• Android Developer Tools offer a full Java IDE with advanced features

for developing, debugging, and packaging Android apps

• Open marketplace for distributing your apps• One time 25$ developer registration fee

5

Version History

Cupcake Donut Eclair Froyo Gingerbread Honeycomb

1.5API LVL 3

1.6API LVL 4

2.0 – 2.1API LVL 5-7

2.2 – 2.2.3API LVL 8

2.3 – 2.3.7API LVL 9-10

3.0 – 3.2.6API LVL 11-13

Major (3) Minor Major Minor Major (9) Major (11)

6

Ice Cream Sandwich Jelly Bean KitKat Lollipop

4.0 - 4.2API LVL 14-15

4.1 – 4.3.1API LVL 16-18

4.4 – 4.4.4API LVL 19-20

5.0 – 5.1.1API LVL 21-22

Major Minor Minor Major

Each version of Android introduces new features. Some include smaller changes, optimizations and bugfixes while others greatly update the

operating system architecture.

Android SDK

• The Android SDK provides access to the API libraries and developer tools necessary to build, test, and debug apps for Android.

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

• Available Tools• ADT Bundle (based on Eclipse IDE)

• Support being Discontinued

• Android Studio (IntelliJ IDEA)• Recently, Google accepted Android Studio as its official IDE.

• `

• NOTE: You only need one of the development tools!

7

Device Testing Reminders:

• Windows:• See OEM USB Drivers document if drivers are necessary.

• MTP : Media Transfer Protocol

• Mac OS:• Android File Manager.

• PTP : Picture Transfer Protocol

• Enable USB debugging on your device.• On most devices running Android 3.2 or older, you can find the option

under Settings > Applications > Development.

• On Android 4.0 and newer, it's in Settings > Developer options.

Note: On Android 4.2 and newer, Developer options is hidden by default. To make it available, go to Settings > About phone and tap Build number

seven times. Return to the previous screen to find Developer options.

8

Installation(Android Studio)

9

Installation

• Download and Install Android Studio

• Just keep pressing next/accept

• Select your UI

• Update the tools

• Done!

10

Creating a ProjectAndroid Studio

11

The First Simple App: “Hello World!”

12

Select “Start New A.S. Project”

13

Package name displayed on Google Play

Project Name viewed on Project List

Domain of the group developing the app

The developer name is generally based on reverse .com domain hierarchy.

[country code].[top level domain].[business name].[subdomain].[team]

Ex: br.com.firasoft.msp.jimmyfive

• Country Code, Subdomain and Team Fields are optional.

The package name is produced from Application Name and Company Domain.

You can edit the Package Name if necessary

14

Project SDK Version

Use API LVL 15 during the tutorial.

After learning the ropes, you can develop andpublish apps for multiple variations of the AndroidOS.

15

Activity Template

Special types of activities which haveminimum elements for their view (UI)

Select a Blank Activity for this exercise.

If you’d like to have special activities youshould update the minimum SDK version.

Example: Full screen Applications Startedbeing supported on 4.4 (API LVL 19)

16

You can configure the naming scheme ofyour Activity, these details only affect thedeveloper side of things.

This is an opportunity for you to employ theknowledge you are learning in class.

By default Java uses Capitalized Camel Code as astandard for Classes, Interfaces and Camel Codefor Methods and Variables. Check Oracle’s websitefor more details:• http://www.oracle.com/technetwork/java/code

conventions-135099.html

17

Textual XML EditorVisual Editor

Used for changing properties

For managing widgets

Android Virtual Device manager Palette for Buttons, EditTexts, Layouts, …

Current File

Android SDK Manager

Android Virtual Device (AVD)

• An Android Virtual Device (AVD) is an emulator configuration that lets you model an actual device. It consists of :

I. A hardware profile: e.g., whether the device has a camera

II. A mapping to a system image: e.g. which Android version

III. A dedicated storage area on your development machine: e.g. the device's user data

IV.Other options: e.g. the emulator skin, appearance, and so on

18

19

select Window > AVD Manager, or click the AVD Manager icon in the Eclipse toolbar

Click the “+” button to create a new AVD

20

Select a device from the preset list or create your own by clicking the “New Hardware Profile” Button.

21

Hardware Limitations

Some computers limited hardware specs, and might struggle to emulate a device. If you are having issues starting a virtual

machine try one of the following solution:

Change any of the Device’s Configurations (pencil icon):

• Change the Architecture of the emulated device from x86 to armeabi-v7.

• Disable “Use Host GPU”

• Reduce the amount of RAM available (Advanced Settings)

22

Installation(Eclipse + ADT)

(For the sake of time these slides are skipped in class. If you would like to continue with the Eclipse framework, please follow this tutorial)

If you are using Android studio, you can skip this step.

23

Installation

• Download and Install Eclipse

• Just keep pressing next/accept

• Add ADT Plugin to the repository list• https://dl-ssl.google.com/android/eclipse/

• Accept all prompts

• Configure ADT• Install SDK or point to previously installed location

• Configure SDK Manager• Install Necessary Versions (Suggested API 21+)

24

Install Eclipse

25

Add Android ADT to Eclipse

26

Install the Android SDK Tools

27

Creating a ProjectEclipse + ADT

28

The First Simple App: “Hello World!”

29

Select “Android Application Project”

30

will be seen in Android devices

will be seen in Eclipse Package Explorer

an unique name forever (the app’s ID)

31

To add and modify your own icon

To add the app’s first screen (activity)

32

Be sure your icon meets the specifications defined in the Iconography design guide.http://developer.android.com/design/style/iconography.html

We can call this part of the wizard later to

modify the app’s icon

33

Special types of activities which have minimum elements for their

view (UI)

34

If you’d like to have special activities so there should be necessary support in the system

(minimum SDK version)

35

It’s possible to specify the type of navigation for your activity (UI). The necessary elements will be added.

If you’d like to have special activities so there should be necessary support in the

system (minimum SDK version)

36

The app’s icon and other bitmaps files (categorized based of their dpi)

Layout (physical structure) of activities will be put here. It’s based on XML and supported by a visual editor

All resources of the app (e.g. strings) should be registered in these sections (proper files). It helps memory management

and localization.

All Java files include launcher activity and other libs

37

Textual XML EditorVisual Editor

Used for changing properties

For managing widgets

Android Virtual Device manager

Palette for Buttons, EditTexts, Layouts, …

Android Virtual Device (AVD)

• An Android Virtual Device (AVD) is an emulator configuration that lets you model an actual device. It consists of :

I. A hardware profile: e.g., whether the device has a camera

II. A mapping to a system image: e.g. which Android version

III. A dedicated storage area on your development machine: e.g. the device's user data

IV. Other options: e.g. the emulator skin, appearance, and so on

38

Managing AVDs with AVD Manager

• select Window > AVD Manager, or click the AVD Manager icon in the Eclipse toolbar

• Click New to create a new AVD

39

Managing AVDs with AVD Manager (cont.)

• Fill out the details for the AVD and click OK.

• Select AVD Name in the list and click Start (be patient because execution

take time)

40

Emulator

41

User InterfaceBasic Concepts

42

What does android provide?

• Pre-build UI components such as structured layout objects and UI controls

• Other UI modules such as dialogs, notifications, and menus (action bars)

• A mechanism to declare elements (e.g. layouts) through either source code or an XML file Easy and quick to create and manage UIs

Separation of logic from presentation

Reusable

can easily specify different layouts for different screen sizes (and densities, languages,...)

Easy to understand

43

User Interface Elements’ Hierarchy

44

invisible view containers

invisible view containers

usually a UI widget

ViewGroups (Containers) are functional elements used to organize the UI.

Views are themselves the objects displayed on screen, such as textboxes, buttons, etc.

Layouts

• defines the visual structure for a user interface

• Can be declared in either an XML file or source code (runtime)

• Common Layouts Linear

Relative

Web view

ListView

GridView

45

Input Controls

• Android provides lots of inputs controls.

• You can build you own custom components.

• Common input controls Button

Text field

Checkbox

Radio button

Toggle button

Spinner

Pickers

46

Second AppSimple Calculator: Time to work!

47

Working with your UI

• The purpose of this task is to teachyou to use the tools available.

• Your android application does not needto look exactly like the one in theexample, but it needs to function as acalculator.

• To add a new object to your interface,drag the component from the Paletteto the Component Tree.

• Never drag components to the preview,Always to Component Tree.

• If you drag a component to the androidpreview screen it will very likely mess thewhole interface and make it harder for youto complete the task at hand

• Don’t forget to show your TA the appwhen you are done.

48

Simple Calculator : Layout

1.Follow the steps in the first example and choose the name “Simple Calculator” for Application Name.

2.Remove TextView “Hello World”

3.Add a Layout (Vertical) under “resultEdit” and assign Id “mainlayout” to it

4.Add an EditText to MainLayout and change its id to “resultEdit”1.Text Field >> PlainText is the standard EditText object.2.To edit a property in an object you can double click it in the preview panel or in the

properties table.

5.Change ResultEdit’s “layout:width” property to fill_parent1.This will make your textfield occupy the whole width of the screen

(In Eclipse, use Outline environment for better managing of components)

49

Simple Calculator : Step 01 Result

50

Simple Calculator : Buttons

1.Add a HorizontalLayout to the VerticalLayout and name it “ButtonsLayout01”

1.Add four buttons to the HorizontalLayout you just created.

2.Rename Each buttons Id to the appropriate “btn0X “ name1. (e.g.: Button 1 will be called “btn01” and the Equals button “btnEQ”)

At this point your buttons might look unbalanced, with the last ones added being flattened on the right side of the screen. That is because the other

buttons are taking all the space available. To fix this do the following:

1.Change the property “layout:weight” in each button to 1.1.Now all buttons should be allowed the same space on the screen

regardless of the text in them.

51

Simple Calculator : Step 02 Result

52

Simple Calculator : More Buttons

1.Repeat the steps in the previous slide 3 times to create a 4 by 4 button matrix.

You will notice that the next row of buttons also get flattened, but this time to the bottom. To solve this issue, give the The HorizontalLinearLayouts the

same weight (layout:weight = 1) in the properties panel.

2. Add an extra button bellow the lowest HorizontalLinearLayout(this will be the Equals Button)1. Set the layout:width to fill_parent.

3. To fill any vertical empty space between buttons set their layout:height property to “fill_parent”

53

Simple Calculator : Step 03 Result

54

Simple Calculator : Buttons

• Change the text of all buttons as you can see in the picture.

• Change the id of all buttons as following:

• The numbers’ id should be started with “btn0”+its number. For example, for 1 button’s id should be “btn01”, for 0 should be “btn00”, and so on.

• For others see the table to the side.

55

Symbol ID

"C" btnClear

"." btnDot

"+" btnAdd

"-" btnMinus

"*" btnMultiply

"/" btnDivide

"=" btnResult

Simple Calculator : Strings

• To separate strings from the layout code, follow these steps:1. Select a button in component tree section and click on it.

2. Navigate to the “Text” property in the properties panel.

3. Select the text property and click the triple dots button.

4. Select “New Resource” and then “New String Resource” in the Resources Window.

5. Define a name for the new button name (e.g.: button_07), add the actual button value (e.g.: 7), save the new resource.

6. Repeat this process for all numbers and operands.

56

Simple Calculator (cont.)

• Add all onClick methods to MainActivity.java file.

• The methods’ signature should be as following:Public void <<methodName>>(View view) {

}

• E.g. onClick method for btnResult is:Public void btnResultClick (View view) {

}

• Don’t forget to import “android.view.View” and “android.widget.EditText”

• Now copy the code in the slides below to match the description above in your .java file.

57

Simple Calculator (code section 1)

58

Simple Calculator (code section 2)

59

Simple Calculator (code section 3)

60

Simple Calculator (code section 4)

61

Simple Calculator (code section 5)

62

Simple Calculator : Input Events

• Each view has its own Events (e.g. onTouchEvenet()) and must be override in order to have your own implementation.

• Instead of extending a view to have control events, use even lisetners

• An event listener is an interface in the View class thatcontains a single callback method. These methods will becalled by the Android framework. onClick() onLongClick() onFocusChange() onKey() onTouch() onCreateContextMenu()

63

Simple Calculator : Button Functions

In order for your buttons to run the code in the java file they need to know what function they should call. To do so:

• Add onClick property to all buttons• In the “Design” view Set onClick property in the Properties panel to the

corresponding function name in the code.• E.g.: the function btn01click() corresponds to button01, so the OnClick

property should read “btn01click”.

• If you check the text version of the interface, you will see something similar to: android:onClick="btn01Click“

• This means that button01 has the correct onclick function assigned to is.

• Repeat this process for all numerical and operator buttons!

64

Android Lab 02Advanced Android Features

65

Class Plan

• Activities

• Intents

66

How to Have Multiple Activity

• Create a simple project with name “Multiple Activity”

• Remove TextView “Hello World”

• Put a small button on the center of screen and name it “btn1”

• Add the property “OnClick” to btn1 (like this android:Onlick=“btnClick”;)

• Add the text of btn1 as a resource value (with CTRL+1)

• Add method btnClick to MainActivity.javapublic void btnClick(View view){

}

• Import android.view.View;

67

How to Have Multiple Activity (cont.)

1.Right click on the project in Project Explorer

2.select New > Other

3.Select “Android Activity” form Android section and click Next

4.Choose Blank Activity and click Next

5.Fill out names as the picture

6.Accept pending changes and click finish

68

Intents

• Messaging Objects designed to request actions from other app components

• Intent use-cases• To start an activity

To start a service

To deliver a broadcast

• Intent types Implicit

Explicit

69

Intent (cont.)

• The primary information contained: Component name

Action

Data

Category

Extra

Flags

http://developer.android.com/guide/components/intents-filters.html

70

How to Have Multiple Activity (cont.)

• Add following code to method “btnClick”Intent intent = new Intent (this,SettingActivity.class);

startActivity(intent);

• import android.content.Intent;

• Run the project as Android Application

71

How to update the app icon (Eclipse)

1.Right click on the project in Project Explorer

2.select New > Other

3.Select “Android Icon Set” form Android section

72

Be sure your icon meets the specifications defined in the Iconography design guide.• http://developer.android.com/design/style/iconography.html

How to change the icon of a created project (cont.)

73

Menus and Action Bar

• Beginning with Android 3.0 (API level 11), Android-powered devices are no longer required to provide a dedicated Menu button.

• Different kinds of menus Option menu and action bar (e.g. search, compose mail,

settings, etc.) Context menu and contextual action mode

It appears when the user performs a long-click on an element and provides actions that affect the selected content or context frame

Popup menu Actions in a popup menu should not directly affect the corresponding

content. Rather, the popup menu is for extended actions that relate to regions of content in your activity

• Menus and items are defined in an XML file

74

Menus and Action Bar (Cont.)

• Two ways to handle click events• Override onOptionItemSelected()

• Define the on-click behavior for a menu item in XML (Android 3.0 and higher)

75

Dialogs

• Dialogs prompt the user for decisions or additional information required by the app to continue a task.

• Different dialogs AlertDialog

You can also add lists

DatePickerDialog

TimePickerDialog

Custom Layout

76

• Simple feedback about an operation in a small popup

• They automatically disappear after a timeout

• You can position the toast differently or even use your own layout instead of a simple text message.

Toasts

77

Settings

• Allow users to modify app featuresand behaviors. For example, howoften the application syncs data withthe cloud.

• Allow to build an interface that'sconsistent with the user experiencein other Android apps (including thesystem settings).

78

Interested in Learning more?

• Follow the Android Training Guide• https://developer.android.com/training/index.html

80