Practical Flutter Improve your Mobile Development with Google’s Latest Open-Source SDK — Frank Zammetti www.allitebooks.com Practical Flutter Improve your Mobile Development with Google’s Latest Open-Source SDK Frank Zammetti www.allitebooks.com Practical Flutter: Improve your Mobile Development with Google’s Latest Open-Source SDK Frank Zammetti Pottstown, PA, USA ISBN-13 (pbk): 978-1-4842-4971-0 ISBN-13 (electronic): 978-1-4842-4972-7 https://doi.org/10.1007/978-1-4842-4972-7 Copyright © 2019 by Frank Zammetti This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. 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For more information, reference our Print and eBook Bulk Sales web page at http://www.apress.com/bulk-sales. Any source code or other supplementary material referenced by the author in this book is available to readers on GitHub via the book’s product page, located at www.apress.com/9781484249710. For more detailed information, please visit http://www.apress.com/source-code. Printed on acid-free paper www.allitebooks.com I’d like to dedicate this book to butterflies, which flutter in the wind. No, wait, that’s too easy. I’d like to dedicate this book to gamblers who, the British people might say, make “a flutter on the horses.” Yes, that’s actually a real usage of the word flutter, but that too is too easy. No, I’d like to dedicate this book to all the unknowns the human race has yet to discover and, in some cases, create. I am a pessimist by nature, but I fight that nature each and every day because I also recognize that the universe is a wondrous place and, despite what the evening news tells us, the human race is capable of great beauty and wondrous creation. And, with my stated goal of being immortal, because death just isn’t me – it’s been done before, so I’m just gonna go ahead and skip it – I look forward to seeing it all! www.allitebooks.com Table of Contents About the Author ..................................................................................................... xi About the Technical Reviewer ............................................................................... xiii Acknowledgments ...................................................................................................xv Introduction ...........................................................................................................xvii Chapter 1: Flutter: A Gentle Introduction .................................................................. 1 Meditations on the Abyss .............................................................................................................. 1 What’s in a (Silly) Name? .............................................................................................................. 3 Dart: Language of the Gods? ......................................................................................................... 5 Widgets to the Left of Me, Widgets to the Right! ........................................................................... 8 Brass Tacks: The Pros and Cons of Flutter .................................................................................. 13 Ok, Enough Talk, Let’s Get Going with Flutter! ............................................................................ 17 Flutter SDK ............................................................................................................................ 17 Android Studio ....................................................................................................................... 19 The (Slightly Less) Typical “Hello, World!” App ............................................................................ 20 Hot Reload: You’ll Love It! ............................................................................................................ 29 Basic Flutter Application Structure ............................................................................................. 31 A Few More “Under-the-Covers” Details ..................................................................................... 35 Summary .................................................................................................................................... 36 Chapter 2: Hitting the Bullseye with Dart ............................................................... 37 The Things You Must Know ......................................................................................................... 38 No Comment: All About Comments ........................................................................................ 39 Nothing Stays the Same: Variables ........................................................................................ 41 Everybody Has a Type: Data Types ......................................................................................... 44 v www.allitebooks.com TABLE OF CONtENtS When a Single Value Just Won’t Do: Enumerations ............................................................... 50 What’s Your Type: The “as” and “is” Keywords ..................................................................... 51 Going with the Flow: Flow Control (and Logic!) Constructs ................................................... 51 The Big Nothing: void ............................................................................................................ 54 Smooth Operators ................................................................................................................. 55 Classing the Joint Up: Object Orientation in Dart .................................................................. 58 Getting Funky with Functions ................................................................................................ 67 Tell Me Is It So: Assertions ..................................................................................................... 71 Out of Time: Asynchrony ........................................................................................................ 71 Ssshhh, Be Quiet: Libraries (and Visibility) ............................................................................ 73 Let’s Be Exceptional: Exception Handling .............................................................................. 74 I Have the Power: Generators ................................................................................................ 76 Metatude: Metadata .............................................................................................................. 78 Speaking in General: Generics ............................................................................................... 79 Summary .................................................................................................................................... 80 Chapter 3: Say Hello to My Little Friend: Flutter, Part I .......................................... 83 A Buffet of Widgets ..................................................................................................................... 84 Layout .................................................................................................................................... 84 Navigation ............................................................................................................................. 97 Input ...................................................................................................................................