Category Archives: General

What is inside a .aia project file?

As you may know, you can save your App Inventor project to your local computer using the Projects | Export selected project (.aia) to my computer menu option:

ExportSelected

Use this feature to save a backup copy on your local computer or to share your code with others (email or transfer the file using DropBox – or similar – or merely copy to a USB thumb drive).

What is inside the .aia file?

Surprisingly, the .aia file is just a regular .zip file. You can verify by saving a copy to your local disk drive, and then rename the file to have a .zip file extension instead of .aia. Then use Windows Explorer, StuffIt Expander or other utility to open and decompress the .zip file.

PLEASE NOTE – DO NOT MODIFY THE CONTENT OF THESE FILES.  THIS INFORMATION IS NOT SOMETHING YOU NEED TO KNOW TO WRITE APP INVENTOR APPS AND IS PROVIDED “AS IS” “FOR YOUR INFORMATION” ONLY.

Continue reading What is inside a .aia project file?

Have App Inventor questions?

If you have questions about App Inventor or App Inventor programming, try posting your questions on the Facebook page “wall” and also here in the comments (I will be working to have the comments cross linked between this web site and FB eventually).

Also check out these two online forums:

Carlos has posted a good question about a problem with Bluetooth communications. If you can help, add a comment there.

 

Raspberry Pi 2 (US $35) computer board features Scratch

Raspberry Pi 2 is a US$ 35 computer board to which you attach a monitor, keyboard, mouse and Ethernet connection. You can use the Pi 2 for web browsing and other functions, but it also comes with Scratch.

Scratch is a programming system that is very similar to MIT App Inventor. You can learn more about Scratch in our previous post on that topic!

But because one of Raspberry Pi’s goals is to advance computer science education, there’s a few pieces of bundled software that can help achieve that goal. This includes a drag-and-drop visual programming language called Scratch (great for beginners to create animations and games), as well as Sonic Pi (for creating electronic music) and more advanced programming languages like Python (also included).

via Surf Report: Taking a bite out of Raspberry Pi.

And speaking of STEM, here are some videos from yesterday’s Oregon City FRC FIRST Robotics Pacific Northwest District 2 (Oregon) robotics competition. 35 high school robotic teams took part, with Team #4488 “Shockwave” taking first by total points. I am biased: I am a volunteer engineering mentor with the Shockwave team, from Glencoe High School, Hillsboro, Oregon. Go Shockwave!

Continue reading Raspberry Pi 2 (US $35) computer board features Scratch

Pevest App Inventor web site now features Google Translate: Translate into many languages!

Interest in MIT App Inventor is growing rapidly, world wide. Many of the readers of this web site do not speak English as their native language.

To help you use the tutorials on this web site, please use the new Google Translate option in the column on the right side of every page.  Select your language and this page will be automatically translated.

My native language is English. I speak a little Spanish that I learned when I was much younger, in high school. I expect to begin reviewing Spanish and improving my Spanish skills soon.

Update: Reading and writing text files with App Inventor

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.

App Inventor Alert: Problems loading projects?

From the MIT App Inventor web site:

Summary: We have been having problems with storing “assets” image, sounds and other objects that you upload to your projects. We are working with Google to resolve these problems as soon as possible.

Things to be aware of:

If we fail to read an asset when you load your project, we substitute a zero-length file. Be careful exporting your projects, as assets may be missing from the “.aia” file exported. Make sure you keep a local copy of your assets on your own computer.

We have been making modifications to the system to mitigate the worst of the problems. In particular we will never serve up a missing asset to the “buildserver” when you package an App. This ensure that if you successfully package an App, the resulting APK is valid. If we fail to read an asset, you will get a “Build Failed” message. If this happens, just keep trying the build. It may work the second or third time around. If it never seems to work, you can remove your assets from your project and upload them again. This may help.

via Problems loading projects?.

December 8-14 is Computer Science Education Week

The Computer Science Education Week coincides with the “Hour of Code” initiative. This example lesson is based on MIT’s Scratch (which is similar to App Inventor).

There are 33 introductory tutorials available for the “Hour of Code” project (teachers may optionally create their own as well).

One of the official tutorial opportunities is based on App Inventor.

Use caution in interpreting the hype over “Hour of Code”. It’s a primitive introduction to some limited programming concepts; many of the tutorials have limited association with computer science. If your expectations are set appropriately, its fine.

Google expected to introduce new Java compiler

The upcoming Jack & Jill compilers in Android | Saikoa.

Most Android apps are written in the Java programming language. Google’s Android software development system converts “source code” (a text file) written in Java, into the code that runs on the Android device.

In many programming language systems, source code is converted into the “machine instructions” of the processor. The processor does not speak “Java” but speaks its own language. A program called a “compiler” converts the original program source code into the “machine language” of the processor.

Many programs for Windows, for example, have been converted into the individual instructions that are processed by an Intel or AMD processor. The “compiler” converts the program source code into a .exe file that contains the machine language instructions of the Intel and AMD processor.

But what if you wanted your program to run on a hardware device that has a Qualcomm or ARM processor?

Continue reading Google expected to introduce new Java compiler

What are the hot programming languages for today

Here is an easy to read report on which programming languages are now “hot” in the market for software developers: Don’t Rely On Salary Data To Pick A Programming Language To Learn – ReadWrite.

The pace of change in software development is rapid – popular languages today may already be fading.  Pay scales for some niche languages are very high (such as Ruby)- but the market opportunity might not be large or lengthy.

Web applications and mobile applications are the “hot” categories. Within those categories, there are a variety of currently popular software development tools:

Continue reading What are the hot programming languages for today