Head First Android Development · 3rd Edition by Griffiths, David -- Read -- Imperial Library of Trantor

Index

1. getting started: Diving In

Welcome to Androidville

Layouts define what each screen looks like Activities define what the app does Extra resources may be needed too

Activities and layouts form the backbone of your app Here’s what we’re going to do Android Studio: your development environment

You need to install Android Studio

Install Android Studio Build a basic app How to build the app

1. Create a new project 2. Choose your project 3. Configure your project

You’ve created your first Android project Dissecting your new project

The folder structure includes different types of files

Introducing the key files in your project Edit code with the Android Studio editors

The code editor The design editor

The story so far... How to run the app on a physical device

1. Enable USB debugging on your device 2. Set up your computer to detect the device 3. Use a USB cable to plug your device into your computer 4. Run your app

How to run the app on a virtual device Create an Android Virtual Device (AVD)

Open the Android Virtual Device Manager Select the hardware Select a system image Verify the AVD configuration The virtual device gets created Run the app on the AVD

Compile, package, deploy, run Test drive What just happened? Refine the app

The app has one activity and one layout The activity controls what the app does The layout controls the app’s appearance

What’s in the layout?

The design editor The code editor

activity_main.xml has two elements Update the text displayed in the layout What the code does Test drive Your Android Toolbox

2. building interactive apps: Apps That Do Something

Let’s build a Beer Adviser app Here’s what we’re going to do Create the project We’ve created a default activity and layout A closer look at the design editor Add a button using the design editor

Changes in the design editor are reflected in the XML

activity_main.xml has a new button

Buttons and text views are subclasses of the same Android View class android:id android:layout_width, android:layout_height android:text

A closer look at the layout code The <LinearLayout> element

The Button element The TextView element

Let’s update the layout XML The XML changes are reflected in the design editor Test drive There are warnings in the layout...

...because there’s hardcoded text

Put text in a String resource file

Android Studio helps you extract String resources

Extract the String resource

A String resource has been added to strings.xml

activity_main.xml uses the String resource

You also can extract String resources manually

Add and use a new String resource Test drive Add values to the spinner

Adding an array resource is similar to adding a String

Add the string-array to strings.xml

Get the spinner to display the array’s values

The full code for activity_main.xml Test drive We need to make the app interactive What our MainActivity code looks like A button can listen for on-click events...

...using an OnClickListener

Get a reference to the button...

...and call its setOnClickListener method

Pass a lambda to the setOnClickListener method How to edit a text view’s text

How to get the spinner’s selected value

The updated code for MainActivity.kt What happens when you run the code Test drive Add the findBeers function The full code for MainActivity.kt What happens when you run the code Test drive Your Android Toolbox

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