Downloading the Android SDK

SDK stands for Software Development Kit. The Android SDK contains tools for developing Apps for Android telephones.

There are pretty complete instructions for downloading the SDK in almost every Android reference, because you really can't begin software development without having most of the tools.

You'll notice that there are choices about what to download. I'll tell you what I've downloaded, but if you like another choice, feel free to take it.

I'd like you to prepare a journal describing your download experience (see end of this page) so at the very least you should take notes as you do the various steps.

The page to start from is

This page has most of its important content hidden behind expandable headings. For example, if you click on the SYSTEM REQUIREMENTS heading, you'll see a list of operating systems and development tools supported for the Android SDK. If you don't have one of the listed operating systems, you might still succeed in getting the development tools to work, but you are committing yourself to extra work!

Downloading Java

Android applications are (mostly) written in Java, so you need a Java set of Java development tools. (A JDK) In particular, as of August, you need Oracle's JDK 6, which is not the latest version, and which you might not have on your system if you have been developing Java programs already. [The reason you need an older version is that Android phones use an independently developed Java Virtual Machine, called Dalvik VM. Dalvik uses a slightly different set of bytecodes, and packs them slightly differently. But instead of writing another compiler to produce Dalvik binary code, Android uses a binary-to-binary file converter, which reads .class files and writes .dex files for the Dalvik VM to use. Although there isn't any reason a similar converter couldn't be written for Java 7 or 8, or the existing converter upgraded to cover any binary differences between the versions, it hasn't been done and tested yet. For the same reason, you can't use gcj, the Gnu Java compiler.]

If you already have another version of Java on your system, and want to keep it, your life just got more complicated. There's no problem with keeping two versions of Java in separate directories, unless you actually want to use them both.

In Windows, there's a Java directory, using in Program Files, and all the downloaded versions sit inside that directory. To use a particular version, you need to make sure that the path is set correctly and that the environmental variables JAVA_HOME and CLASSPATH are set to match.

On linux, that scheme would work most of the time if it weren't a convention to put a soft link in /usr/bin/javac (and /usr/bin/java and /usr/bin/jar, etc.) to the current version. So you need to redo the soft link when you want to switch between versions. To make this easier, there's a tool called update-alternatives, which fixes the soft links if you follow a set of conventions about where you put the software, and since there are so many different java tools, there's a tool called update-java-alternatives which calls update-alternatives on about twenty different java tools if you have its configuration file set up correctly.

To be lazy, I'm going to assume that you're willing to have only one version of Java on your system; if you already have another, you'll leave the JRE around for programs you've previously compiled, but never use the JDK for that version again.

To download software from Oracle, you need an Oracle user account. Go to, and either sign in, or click on the Create Account button. The account is free, although presumably Oracle is hoping to send you advertising once you give them your email address.

To download JDK 6, you need to go to You might as well download the latest version of Java 6, even though you are scores of versions behind the latest version of Java 8. That's Java SE Development Kit 6u45. After you click on the link, you'll have to choose the Accept License Agreement radio button, and the appropriate OS and hardware version.

If you are running a 64-bit Windows system (pretty likely if you bought your machine in the last three years) you want the Windows x64 download, jdk-6u45-windows-x64.exe. It is a self-installing executable, but you'll need an administrative password to install. I think it sets up the path, etc. so that all you have to do is run it.

Linux X64 has two files to pick from. If you were running redhat linux or one of its derivatives, you'd want the file with rmp in the name; I'm running ubuntu, and chose the other. The .bin extension indicates that the file is intended to be run as a shell script, so once you've downloaded it, you'd

chmod +x jdk-6u45-linux-x64.bin ./jdk-6u45-linux-x64.bin

Downloading ADT

I have a linux system, and I chose to download the Linux 64-bit bundle, which includes a fresh copy of the eclipse debugger, with all the Android plugins already installed.

If you have Windows on your machine, you will obviously want to download a Windows version of the software. If you happen to have a 32-bit processor, that is also relevant to your choice.

If you already have eclipse installed on your machine, you can save a little network traffic by downloading only the SDK. This would also be your choice if you are planning to skip using eclipse. The main advantage in doing so is that you understand exactly why a particular tool didn't get run -- you didn't run it. Eclipse tries not to do any duplicate work, and sometimes it doesn't do what you expect it to. On the other hand, eclipse is well connected to the documentation, and will save you a lot of search time.

A side-bar invites you to consider downloading Android Studio instead. It isn't a silly idea, but I decided not to do it.

The Example code from the text

The authors have made machine-readable versions of much of their code available online.

The example code is on github, a public code repository. The URL is

You don't need to download any of their code for the course. Almost all of it is in the textbook. But it's instructive to read it anyway, it's interesting to compile and play with it, and you sometimes use it as skeleton to start your own systems.

Testing your installation

In order to test your installation you should write the minimal android hello world program.

What to turn in

I'd like to see a journal describing your download and testing effort. It can be a Word document, a web page, or an archive of text and image files. It should contain:
  1. A text description of your steps, successes, and problems. You don't need to retype everything I already said; you can just reference it if you want.
  2. A few illustrations, perhaps screenshots.
  3. listings of code, xml files, etc. which you modified for the Hello World app.
You'll notice that wordy as I was, I missed many steps. Surely you will document them ...