The Android SDK or Software Development Kit is run by the Java computer language underneath App Inventor. It's what makes things like our neat app creation by simply pulling together blocks and the use of an emulator as a test device possible.

Normally, we could care less in the same way we drive a car without thinking about what position the pistons are in and if the spark plugs spark. Still, the SDK is there for our use.

On Windows computers, the SDK should be in the c:\program files\android directory if you installed it as suggested in Chapter 1, Obtaining and Installing Google App Inventor. Clicking on the SDK Manager.exe opens the main SDK program.

Using this program, you can do things such as install additional emulators for use in Blocks Editor. For example, in mine I've added an emulator for the Galaxy tablet computer as shown in the next screenshot (see Chapter 1, Obtaining and Installing Google App Inventor again for more details).

Oh, and also check SDK Manager.exe occasionally to make sure all updates have been applied.

If you actually want to program in Java directly, you'll want to install Eclipse, an open source IDE (Integrated Development Environment) that makes it much easier to work with Java and the SDK.

Of perhaps more immediate use to you is the ddms.bat batch file (found in the tools directory), which opens the Dalvik Debug Monitor as we saw earlier in the book. It does several nice things including screen captures of your test device as shown in the following screenshot, and it is indispensible if you are creating art for the apps you post on Market.