Category Archives: Documentation

Documentation, General, Products, STEM Education

App Inventor 2 Tutorial Volume 2 is now available at Amazon

Volume 2 of the App Inventor 2 Tutorial is now available at Amazon as an e-book via this link: App Inventor 2 Tutorial Volume 2: Step-by-step: Advanced features including TinyDB.  The e-book will also be available from Google Play shortly.

Description

MIT App Inventor 2 is a fast and simple way to create custom Android apps for smart phones or tablets. Volume 2 in the series introduces debugging methods, explains additional controls not covered in Volume 1, introduces “agile” methods for developing a real world app, and provides sample code for using the TinyDB database.

The App Inventor 2 Tutorial series is targeted at adult learners (high school and up). App Inventor 2 provides a simplified “drag and drop” interface to layout your app’s screen design. Then implement the app’s behavior with “drag and drop” programming blocks to quickly assemble a program in a graphical interface.

Volume 1 of this series covered the basics of the App Inventor user interface Designer and the Blocks programming editor, plus basic “blocks” programming concepts and tools for arithmetic, text processing, event handling, lists and other features. Volume 2 builds upon Volume 1 to provide tips on debugging programs when the apps work incorrectly, how to use hidden editing features, and how to install your own apps on to your phone or tablet for general use. Code samples are provided for using the Notifier component for general use or for debugging, for user interface control tricks such as buttons that change color continuously or implementing the missing “radio buttons” component, using ListPicker and Spinner for list selections, and using the WebViewer to display web pages in your app. The book includes a large section on designing and building a sample real world application and finishes with a chapter on using the TinyDB database.

For readers of the blog, Chapters 4–8 are based on the tutorial already presented here. Chapter 2 and Chapter 9 on TinyDB are all new material.

Chapters

  • Introduction
  • Chapter 1 – App Inventor Tips
  • Chapter 2 – Debugging App Inventor Programs
  • Chapter 3 – User Interface Control Tricks
  • Chapter 4 – Designing and Building a Real World Application
  • Chapter 5 – Tip Calculator Version 2
  • Chapter 6 – Tip Calculator Version 3
  • Chapter 7 – Tip Calculator Version 4
  • Chapter 8 – Tip Calculator Version 5
  • Chapter 9 – Using the TinyDB database

(Volume 3 is now available – App Inventor 2 Databases and Files adds substantially more information on TinyDB, plus TinyWebDB and Fusion Tables and includes the full introduction to TinyDB).

AppInventor_Volume2Cover

Android Development, Documentation, General, Programming Method, Tips

Update: Reading and writing text files with App Inventor

2 Comments

I previously posted a short tutorial on writing to and reading from text files stored on an Android device, using an App Inventor app.

Unfortunately, as some comments noted, the file being created seems to disappear – the data is written and can be read back – but the file is no where to be found on the phone!

After some research, I now know where the file is – and also how to copy the file from the phone (or tablet) to your personal computer.  While the solution to finding and saving the file to your computer is ultimately easy, I need to update the tutorial and explain some things about the Android file system. You will also need to install a free app on your phone in order to copy the file to your computer.

I have posted an updated tutorial that explains the details and shows how to store your files in the right location, how to find them (they are hidden from most views), and how to copy them to your personal computer.

Components, Documentation

Using Lists in App Inventor

A frequent search topic on this blog is how to use lists. “Lists” are a way of storing a collection of data in App Inventor programs. Many other programming languages provide a number of methods for storing collections of data including arrays, records, even lists, and even something called “collections” (imagine that!)

App Inventor provides Lists, plus you can also use components like the TinyDB.

For a detailed description of using Lists, please refer to Chapter 8 – Introduction to Lists in my e-book “App Inventor 2: Tutorial”, available for $2.99 from Amazon. I hope to make this text available in additional e-reader formats during November.

Components, Documentation, Tips

Display “Warning” and “Alert” box messages in App Inventor apps

17 Comments

Whether you use Windows, Linux or Mac OS X applications, when the program needs to alert the user (you!) to an issue, the program displays a pop up dialog box with a warning or error message. You can easily create similar warning messages in App Inventor, as shown in this example screen:

Screenshot_2014-09-08-14-05-48

To create a pop up warning dialog, use the Notifier control that appears in the Designer’s Palette:

NotifyPalette

Drag the Notifier icon into the app user interface design – the Notifier is used as a non-visible component, just below the user interface:

NotifyDesignerView

Switch to the Blocks view, click on the Notifier1 block to view the available methods. A partial list of methods is shown here – the item circled in red is the one we will use in this example:

NotifierMethods

In response to an on screen button press (btnNotifyUser’s Click event), the app displays the dialog message:

 

NotifyBlockCodeThis block can be inserted anywhere a processing block is allowed such as the result of an if-then-else conditional block. You can also change the text or background color of the app to something more interesting than the “black and white” default colors shown in this example.

Notifier provides a quick and easy way to display short alert messages to the user of the app.