Android Runtime
Some of the higher-level components of Android in the Application layer
(described next) interact directly with the libraries just described. Other parts
of the Application layer interact with the libraries via the Android Runtime.
Android software is primarily written in Java, using Google-developed and -
specific Java libraries. That software runs on the Android Runtime, composed
of some additional core libraries running on top of a special virtual machine
called Dalvik. The core libraries provide most of the functionality of Java.
Dalvik performs just-in-time (JIT) compilation and is optimized for mobile
devices.
Application Framework
The Application Framework is a set of useful systems and services that top-
level applications can call. These systems and services provide standardized
means of accessing system information, using device hardware, creating
notifications, and so on. They are the same set used by the core applications
included in Android, so end-user-created applications can have the same look,
feel, and interaction style as those provided by Android.
Applications
Android comes with a set of core applications, including a web browser,
programs for text messaging, managing contacts, a calendar, an email client,
and more. As noted earlier, Android software is written in Java.
Installing Android Studio
Android provides a bundled integrated development environment (IDE) with
the software development kit, which is a set of tools to enable the creation of
applications to run on Android. Android Studio has versions available for
Linux, macOS, and Windows.
Installing Android Studio
Download the latest version of Android Studio from the Android Developers
website, at http://developer.android.com/studio/index.html. For Ubuntu, you
need the Linux version, which is made available as a .zip file. Unpack the
file in the location where you want the development kit to reside (for