Flutter For Dummies

CREATE AWESOME IOS AND ANDROID APPS WITH A SINGLE TOOL!

Flutter is an app developer’s dream come true. With Google’s open source toolkit, you can easily build beautiful apps that work across platforms using a single codebase. This flexibility allows you to get your work out to the widest possible audience. With Flutter already being used by thousands of developers worldwide in a market where billions of apps are downloaded every year, now is the right time to get ahead of the curve with this incredible tool.

Flutter for Dummies is your friendly, ground-up route to creating multi-platform apps.

From how to construct your initial frameworks to writing code in Dart, you’ll find the essentials you need to ride the Flutter revolutionary wave to success. This book includes how to create an intuitive and stunning UI, add rich interactivity, and easily pull in data. You’ll also see how Flutter features like Hot Reload—providing sub-second refreshes as you refine your work—help you make sure your app is a delight to use.

* Start simple: follow steps to build a basic app
* It’s alive! Keep connected to online data
* It moves! Make things fun with animated features
* Get the word out: use tips to expand your audience

Whether you’re a fledgling developer or an expert wanting to add a slick feather to your programming cap, join the Flutter revolution now and soar above the rest!

BARRY BURD, PHD, is a veteran educator and a professor of mathematics and computer science at Drew University. When he's not lecturing at the university, Barry speaks at professional conferences and somehow finds time to write books, including Java For Dummies and Beginning Programming with Java For Dummies.INTRODUCTION 1

How to Use This Book 1

Conventions Used in This Book 2

What You Don’t Have to Read 2

Foolish Assumptions 3

How This Book is Organized 4

Part 1, “Getting Ready” 4

Part 2, “Flutter: A Burd’s-Eye View” 4

Part 3, “Details, Details” 4

Part 4, “The Part of Tens” 4

More on the web! 5

Icons Used in This Book 5

Beyond the Book 6

Where to Go from Here 6

PART 1: GETTING READY 7

CHAPTER 1: WHAT IS FLUTTER? 9

Hardware and Software (Things You May Already Know) 10

Where Does Flutter Fit In? 15

Cross-platform development 15

A quick-and-easy development cycle 17

A great way to think about app development 25

Enough New Terminology! What’s Next? 28

CHAPTER 2: SETTING UP YOUR COMPUTER FOR MOBILE APP DEVELOPMENT 29

The Stuff You Need 30

What to Do 32

Getting and installing the stuff 32

For Mac users only 34

Configuring Android Studio 35

Running your first app 36

Dealing with the Devil’s Details 43

On installing Android Studio 43

On launching Android Studio for the first time 44

On installing Android Studio’s Flutter plugin 44

On adding virtual devices 46

On installing Flutter 50

Divisiveness Among Devices 52

Running apps on an Android device 52

Testing apps on a physical device 53

Using Android Studio 59

Starting up 59

The main window 60

Running This Book’s Sample Programs 63

Enjoying reruns 65

If you’re finicky 65

Were These Setup Steps Fun or What? 66

PART 2: FLUTTER: A BURD’S-EYE VIEW 67

CHAPTER 3: “HELLO” FROM FLUTTER 69

First Things First 69

What’s it all about? 72

A constructor’s parameters 75

A note about punctuation 76

Don’t relent — simply indent 77

Classes, Objects, and Widgets 79

A brief treatise on “within-ness” 81

The documentation is your friend 82

Making Things Look Nicer 83

Creating a scaffold 86

Adding visual tweaks 88

Dart’s enum feature 89

Hello from sunny California! 89

Adding another widget 91

Centering the text (Part 1) 94

Centering the text (Part 2) 97

Displaying an image 100

Hey, Wait a Minute 104

CHAPTER 4: HELLO AGAIN 105

Creating and Using a Function 106

The function declaration 107

A function call 108

Parameters and the return value 108

Programming in Dart: The Small Stuff 112

Statements and declarations 112

Dart’s typing feature 113

Literals, variables, and expressions 114

Two for the price of one 117

Dart’s var keyword 119

Built-in types 121

Types that aren’t built-in 123

Using import declarations 123

Variations on a Theme from Die Flutter Mouse 124

Type names in function declarations 127

Naming your parameters 128

What about the build function? 129

More Fun to Come! 130

CHAPTER 5: MAKING THINGS HAPPEN 131

Let’s All Press a Floating Action Button 132

Stateless widgets and stateful widgets 134

Widgets have methods 135

Pay no attention to the framework behind the curtain 139

Enhancing Your App 146

More parameters, please 148

The override annotation 151

What does mean? 152

Anonymous functions 153

What belongs where 156

Names that start with an underscore 160

Whew! 162

CHAPTER 6: LAYING THINGS OUT 163

The Big Picture 164

Creating bite-size pieces of code 167

Creating a parameter list 169

Living color 170

Adding padding 171

Your humble servant, the Column widget 173

The SizedBox widget 175

Your friend, the Container widget 176

Nesting Rows and Columns 181

More Levels of Nesting 183

Using the Expanded Widget 186

Expanded versus unexpanded 189

Expanded widget saves the day 192

Flexing some muscles 196

How Big is My Device? 199

PART 3: DETAILS, DETAILS 205

CHAPTER 7: INTERACTING WITH THE USER 207

A Simple Switch 208

Dart’s const keyword 211

Compatible or NOT? 213

Wait For It! 214

How Much Do You Love Flutter? 217

Dealing with Text Fields 220

Callouts 1 and 2 223

Callout 3 225

Callout 4 226

Callout 5 230

Creating Radio Buttons 230

Creating an enum 233

Building the radio group 233

Displaying the user’s choice 235

Creating a Dropdown Button 239

Building the dropdown button 242

The little Reset button 244

Making a Map 245

Onward and Upward 246

CHAPTER 8: NAVIGATION, LISTS, AND OTHER GOODIES 247

Extending a Dart Class 248

From One Page to Another 251

An icon on a button 254

Pushing and popping 255

Passing Data from Source to Destination 256

Passing Data Back to the Source 261

Dart’s async and await keywords 264

Taking control of the app bar’s Back button 266

Passing Data in Both Directions 267

Creating Named Routes 272

Creating a List 276

The ListView widget 279

Creating list items one-by-one 285

Another new Dart language feature 288

Fetching Data from the Internet 290

Using a public API 293

Sending a URL to a server 295

Making sense of a JSON response 296

What’s Next? 296

CHAPTER 9: MOVING RIGHT ALONG 297

Setting the Stage for Flutter Animation 297

Moving Along a Straight Line 303

Bouncing Around 308

Animating Size and Color Changes 310

Moving Along a Curve 312

Dragging Things Around 314

Where To Go From Here 319

PART 4: THE PART OF TENS 321

CHAPTER 10: TEN WAYS TO AVOID MISTAKES 323

Put Capital Letters Where They Belong 323

Use Parentheses When (and Only When) They’re Appropriate 323

Limit Access to Variables 324

Call setState 324

Make Adjustments for Indices Starting at Zero 324

Use the Expanded Widget 325

Add itemCount to Your ListView.builder 325

Add Imports When They’re Required 325

Declare Assets and Dependencies in pubspec.yaml 325

Indent Your Code According to Dart Language Guidelines 326

CHAPTER 11: TEN WAYS TO ENHANCE YOUR APP DEVELOPMENT CAREER 327

Practice! Practice! 327

Critique Your Own Code 328

Have Others Review Your Code 328

Find Out Which Technologies Your Nearby Companies Use 328

Attend User Group Meetings 328

Ask Questions 329

Ask Yourself Whether You Truly Understand 329

Learn Things That You May Never Need to Know 329

Do What You Love to Do 330

Get Plenty of Sleep 330

CHAPTER 12: TEN CHAPTERS ABOUT FLUTTER APP DEVELOPMENT 331

Introduction 331

What is Flutter? 331

Setting Up Your Computer for Mobile App Development 332

‘Hello’ from Flutter 332

Hello Again 332

Making Things Happen 332

Laying Things Out 332

Interacting with the User 332

Navigation, Lists, and Other Goodies 333

Moving Right Along 333

PART 5: APPENDICES 335

Appendix: Doris’s Dating App 337

Index 347