Android JNI/NDK - notes on getting started

There are a lot of steps required to get your Android development environment set-up, to a state where you can create your first Android "Hello World" app with JNI/NDK.

This is definitely not for the faint-hearted! It is complicated enough that I thought it'd be useful to run through in a blog entry.

So, here is a summary of what to do, in order to get started with using the Android software under both Mac and Windows.

1. Get the latest Sun Java SE Development Kit

Windows: You can get this from here:
http://java.sun.com/javase/downloads/index.jsp

Mac: You should already be up-to-date, assuming you have XCode installed

2. Get Eclipse

I downloaded the latest version of the "Eclipse IDE for Java Developers" from here:
http://www.eclipse.org/downloads/

Windows: Unzip, and then put a shortcut to eclipse.exe somewhere where you can find it!

Mac: Unstuff, and put Eclipse to your Applications folder.

3. Get the base Android SDK (1.5 or later!)

As we're doing to be doing NDK development, make sure you get Android 1.5 or later from here:

http://developer.android.com/sdk/index.html

Make sure you follow the appropriate instructions for installing/upgrading (depending on what current system you might already have)

Windows: When you unzip the file, make sure that it goes under the c:\ root folder... i.e. so it looks like this (for example):

c:\android-sdk-windows-1.5_r3


Mac: Put this under your home folder, so it looks like this (for example):

~/android-sdk-windows-1.5_r3


4. Windows: Get Cygwin

The cygwin toolchain is required for NDK development if you're using Windows.

So, make sure you have cygwin installed! You can get this from here:
http://www.cygwin.org
... note that you'll need the C/C++ developer tool packages.

Mac: users already have a suitable toolchain built-in through XCode.

5. Get the Android NDK

Get the latest Android NDK, from the "Native Development Tools" in the sidebar on in the sidebar on this page:
http://developer.android.com/sdk/index.html

Windows: When you unzip the files, make sure you copy them such that they are under the C:\ root folder, i.e. so that they look like this:

c:\android-ndk-1.5_r1

... if you leave them under e.g. My Documents, then the system will fail to build your source code due to spaces in the file paths etc.

Mac: Put this under your home folder, so it looks like this (for example):

~/android-ndk-1.5_r1


Make sure you follow the instructions that are in DOCS/INSTALL.TXT ...!!!

6. Windows: My Computer - path

Remember to follow instructions on setting your path variable!

Basically, append something like the following (which you'll have to change if you ever come to upgrade)


;c:\android-sdk-windows-1.5_r3;c:\android-ndk-1.5_r1


7. Create your first AVD

You can create your first AVD to be called something like my_android1.5 ... make sure you base it on the Android 1.5 SDK!

You can do this from Eclipse; and more information is available here:
http://developer.android.com/guide/developing/tools/avd.html

Test that you set-up the NDK properly

The following steps will create the following file:

out/apps/hello-jni/android-1.5-arm/libhello-jni.so


Windows:

start cygwin
cd /cygdrive/c/android-ndk-1.5_r1
make APP=hello-jni


Mac:

Run Terminal
cd ~/android-ndk-1.5_r1
make APP=hello-jni


8. Create your first basic Android Project

Now follow the instructions here:

http://developer.android.com/guide/developing/eclipse-adt.html#CreatingAProject

... and if you're lucky, it will build and run, and you can then get on with the JNI/NDK side of things!

9. Create and build/run your first NDK project

You can now create your first NDK project using JNI, and build/run it, following the steps you'll find here:

http://developer.android.com/sdk/ndk/1.5_r1/index.html#samples

Easy!