Android NDK Intoduction

Rahul Tripathi

Agenda

The Android Native Development Kit (NDK)

NDK Info

What , Why , Why not ?

Requirement Tools & Installation of NDK

Developing an ADD application that uses the NDK

Final Output

NDK info Android Native Development Kit (Android NDK)

Developer(s) - Google

Initial release - June 2009; 5 years ago

Stable release -

10d / December 2014; 2 months ago

Written in- C and C++

Operating system- Cross-platform

Available in- English

Type- IDE, SDK

Website-

developer.android.com/tools/sdk/ndk/index.ht

ml

Native Development Kit What , Why ,Why Not?

The NDK is a toolset that allows you to implement parts of your app using native-code languages such as C and C++.

What is it?

Build scripts/toolkit to incorporate native code in Android * apps via the Java NativeInterface (JNI)

Why use it?

Performancee.g., complex algorithms, multimedia applications, games

Why not use it?Performance improvement isn’t alwaysguaranteed, in contrary to the addedcomplexity

NDK Build Process

1. 3.

2.

Dalvik Application

Android NDK Application

What is JNI ?

Android is put together of about equal part Java and C.

we need an easy way to bridge between these two totally

different worlds.

Java offers Java Native Interface (JNI) as a framework

connecting the world of Java to the native code.

NDK - System and Software Requirements

The Android SDK

A complete Android SDK installation (including all dependencies) is required.

Android 1.5 SDK or later version is required.

Supported operating systems

Windows XP (32-bit) or Vista (32- or 64-bit)

Mac OS X 10.4.8 or later (x86 only)

Linux (32 or 64-bit; Ubuntu 8.04, or other Linux distributions)

Required development tools

For all development platforms, GNU Make 3.81 or later is required. Earlier versions of GNU Make might work but have not been tested.

A recent version of awk (either GNU Awk or Nawk) is also required.

For Windows, Cygwin 1.7 or higher is required. The NDK will not work with Cygwin 1.5 installations.

How to Install NDK

On Linux and Mac OS X (Darwin):

Download the appropriate package from this page.

Open a terminal window.

Go to the directory to which you downloaded the package.

Run chmod a+x on the downloaded package.

Execute the package. For example:

ndk$ chmod a+x android-ndk-r10c-darwin-x86_64.binndk$ ./android-ndk-r10c-darwin-x86_64.bin

The folder containing the NDK extracts itself.

Note that you can also use a program like 7z to extract the package.

On Windows:

Download the appropriate package from this page.

Navigate to the folder to which you downloaded the package.

Double-click the downloaded file. The folder containing the NDK extracts itself.

Configure NDKNow Open Eclipse and Configure NDK .

Go to window Option on the top.

Click Preference :

In Android ----> Select NDK ----> Give the path of your

NDK Which you have Extracted by Terminal .

(Note : Please Don't Make any Space in Contains Path Folder)

You have to download For NDK ..

Click Help : Install New Software ----> Select Release / Juno Link ..

Now Select

C/C++ GCC Cross Compiler Support

C/C++ GDB Hardware Debugging

Now Finish ....

Now Start With Project

Create a Android Application Project -->

Right Click on project -->

Select Android tool -->

Add Native Support -->

NDK Project Explorer in Eclipse

Jni FolderC/C++ File

Android.mk file

Application.mk file

After do that, your project has a folder called “jni”. Inside this folder, you have the

Android.mk file, which goes your library configuration for the compiler. And there is a

another file with .cpp (C++) extension, this is where your native code goes.You have to

create A file in side jni folder Application.mk which describe which native 'modules' (i.e.

static/shared libraries) are needed by your application.

Now Here is .Java , .MK

Android.MK & Application.MK

Android.mk :- sub-makefile that describes the C++

static libraries and *.so files you want to build.

Application.mk :- contains settings that apply to

all the C/C++ code (processor type, API level,

standard library, project-wide compiler options)

Calling Native From Java

• Create an activity .JAVA .

• Write A native method in side that Activity .

• JNI program uses a static initializer to load a shared library

("myjni.dll" in Windows or "libmyjni.so" in Ubuntu). It

declares a native method.

Create A JNI .h Header File Using "Javah"Generating C/C++ Header File using "javah" Utility

Now We Have to Create Header File (.h) under JNI Folder .

Using Terminal/Cygwin

Go to your bin directory using cd command .. On Terminal/Cygwin .

No.....

You Can Create Manual Javah Builder ...

Header file for C/C++ Programs

Run javah utility on the class file to create a header file for C/C++ programs.

C/C++ Implementation Write Your C/C++ Code

JNI environment interface function

What is Javah ?

Java is bundled with JDK .it Has command to generate c header file from a

java class. this file provide connective glue that allow your java and c code to

intract.

How to find your Javah from Terminal :

Which Javah

Setting up Automatic NDK Builds in

Eclipse Start by right clicking on your android project and select Properties. In the resulting

dialog, choose the Builders entry in the list to the left and press the New... button:

Here We Go .......... NDK Build

NDK Build Finish ....

Generated

Shared Library .So File

1. The Android OS loads the Java code and starts

executing it

2. The Java code calls System.loadLibrary() to load

a native library.

3. The Java code starts calling functions from the

native code.

Final Output

Thank You