What You Need to Start: Java Programming for Androids
Before you can write Java programs for Android devices, you need some software tools. Some tools are necessary; some are optional. Here’s a list of the tools you need:
A Java virtual machine
Cool people refer to this item as the JVM or simply as Java.
The Java code libraries
These code libraries are known affectionately as the Java Runtime Environment (JRE) or simply as Java.
An integrated development environment
You can create Java programs using geeky, keyboard-only tools, but eventually you’ll tire of typing and retyping commands. An integrated development environment (IDE), on the other hand, is a little like a word processor: A word processor helps you compose documents (memos, poems, and other works of fine literature); in contrast, an IDE helps you compose computer programs.
The Eclipse IDE is great for composing Java programs.
You should also gather these extra goodies:
Some sample Java programs to help you get started
You can download lots of sample code from the Java Programming for Android Developers for Dummies webpage.
The Android Software Development Kit
The Android Software Development Kit (SDK) includes lots and lots of prewritten, reusable Android code and a bunch of software tools for running and testing Android apps.
The prewritten Android code is the Android Application Programming Interface (API). The API comes in several versions — versions 9 and 10 (both code-named Gingerbread), versions 11, 12, and 13 (Honeycomb), versions 14 and 15 (Ice Cream Sandwich), and so on.
Android-oriented add-ons for the integrated development environment
By using add-ons, you customize the Eclipse IDE to help you compose, run, and test your Android apps. The set of Eclipse add-ons for working with Android apps is the Android Development Toolkit (ADT).
All these tools run on the development computer — the laptop or desktop computer you use to develop Java programs and Android apps. After you create an Android app, you copy the app’s code from the development computer to a target device — a phone, a tablet, or (someday soon) a refrigerator that runs Android.