Learning MIT App Inventor

Derek Walter is a freelance writer specializing in the mobile ecosystem. He contributes regularly to PCWorld, Macworld, Greenbot, and other sites devoted to consumer technology. He also blogs about mobile apps and other topics in technology at theapplanet.com. His undergraduate degree is in mass communication/journalism, and he holds a master’s degree in educational technology from The George Washington University. Derek has also worked in education for the last 15 years as a classroom teacher and adjunct university instructor. Mark Sherman is a researcher in computer science education and has taught computing, programming, and robotics to undergraduates in the U.S., India, and China. He is an MIT App Inventor Master Trainer, and he has taught students mobile app design with App Inventor and trained teachers and faculty on best practices and pedagogy of the same. He holds a bachelor’s degree in computer engineering and a master’s degree in computer science, both from UMass Lowell.

Preface     xiv


1 An Introduction to Programming     1
  Operating Systems     2
    User Interface     4
  Android Strengths     6
    Extending App Capabilities     8
    Google Services     9
  Applications     10
  Programming Languages     11
  Summary     13
  Exercises     14
2 Building with MIT App Inventor     17
  The MIT App Inventor Site     17
    Signing In     18
    Designer     20
    Blocks Editor     20
    The AI2 Companion App     21
    The Android Emulator     23
    USB Connection to Android Device     23
  Getting Inside an App     25
    Event Handlers     25
    Doing One Thing at a Time     26
  Exercise: Sherlock Is Watching     27
    Adding an Image     29
  What Can You Build?    31
    Speak, Android!    31
    Pollock     31
    Fore     32
    Android Quiz     32
  Uploading to Google Play     32
  Summary     33
  Exercises     34
3 App Inventor Toolkit     35
  Creating a New Project     36
  Designer Essentials     36
    Palette     37
    Viewer     44
    Components     45
    Properties     46
    Media     46
  Exercise: Speak, Android!    47
    Connecting Your Device     48
    See Your App on a Connected Device     50
  Summary     54
  Exercises     54
4 Variables     55
  Component Properties: The Built-in Variables     56
    Clicker-Counter App     56
    Properties: Getters and Setters     57
    Clicker Counter Extensions     58
  Event Parameters: Special Variables    58
  Exercise: Pollock     60
    The Interface     60
    Programming Blocks     62
    Additional Exercises     64
  Scope: Global and Local Variables     64
  Global Variables     66
    Example App: Up/Down Counter     67
  Local Variables     68
    An Example App: Random Guess     69
  What You Can Store in Variables     72
  Summary     72
5 Procedures     75
  What Is a Procedure?    75
  Types of Procedures     76
  Why Use Procedures?    79
  Arguments     79
  Exercise: Flick     81
  Additional Exercises     83
  Summary     84
6 Working with Lists     85
  Modeling Things with Data     85
    The List Block     85
  The Basics     87
    Creating an Empty List     87
    Creating a List with Some Stuff Already In It     88
    Working with Lists     91
    Color as a List     92
  Types of Lists     92
    The One-Dimensional List     92
    Lists as Data Structures     93
    Using Multiple Lists Together (That Expand on Demand)    94
  Abstraction with Lists and Procedures     98
    Lists that Expand on Demand     100
  Common Problems     102
    Running Off the End of the List     102
    Defining a Variable That Depends on Runtime Elements     104
  Exercise: Android Quiz     105
  Additional Exercises     112
  Summary     112
7 Games and Animations     113
  Adding Animations     113
    ImageSprite     114
    Ball     115
    Canvas     116
  Animation Examples     117
    Smoother Animation     118
    Edges and Collisions     119
  Exercise: Fore     119
  Additional Exercises     123
  Summary     123
8 Multiple Screens and Debugging Techniques     125
  Why More Than One Screen?    125
  Building Apps with Multiple Screens     126
    What Screens Are Good At     127
    Issues with Multiple Screens     127
    Switching Screens     128
    Sharing Data Between Screens     129
  Debugging Techniques     130
    Leaving Comments     130
    Test Small and Test Often     131
    Do It     131
    Name Well     132
  Backing up Your Work     133
  Exercise: Pollock Plus One     134
  Additional Exercises     136
  Summary     136
9 Using Media     139
  Audio     140
  Images     141
    The ImagePicker     141
    The Camera     144
  Video 1    45
  Exercise: Camera Action     146
  Additional Exercises     146
  Summary     147
10 Sensors     149
  Building Location-Aware Apps     150
    Using Location     150
    Location Data     152
    Using the Maps App with Intents     153
    Saving Location Data     155
  The Accelerometer     158
    Detecting Tilt (and a Little Background Physics)    159
  The Orientation Sensor     160
  Exercise: Pushpin     161
    Part 1: Designing Current Location Readout     161
    Programming Part 1: The Current Location Readout     165
    Part 2: Pinning a Location to Remember Later     168
    Programming Part 2: Pinning a Location     170
    Extension Activities     172
  Summary     172
11 Databases     173
  TinyDB     174
    Retrieving Data from TinyDB     175
    A Few TinyDB Details     176
  TinyWebDB     176
    Setting Up Your Own Web Database Service     176
    Security and Privacy     177
  FusionTables     177
  Using Web GET and POST     180
    Basic Files     181
    Web APIs     182
  Exercise: WriteMore     182
  Additional Exercises     186
  Summary     187
12 Distributing an App     189
  Live Mode     189
  Security Settings     190
  Creating an APK File     191
    Downloading Directly to a Computer     192
    Downloading with a QR Code     196
  Creating an .aia File     198
  Exercise: App Distribution     200
    Version Codes     200
    Google Play Developer Console     201
  Summary     205


Index     207