AI 150083: Minor updates to the ndk docs based on approved messaging.

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page.title=Android 1.5 NDK, Release 1

@jd:body

<h2>What is the NDK?</h2>

<h2 id="overview">What is the Android NDK?</h2>

<p>The Android NDK provides tools that allow Android application developers

to embed components that make use of native code in their Android applications.

</p>

<p>The Android 1.5 NDK provides tools that allow Android application developers

to embed and deploy native code within their Android applications. It

provides:</p>

<p>Android applications run in the Dalvik virtual machine. The NDK allows 

developers to implement parts of their applications using native-code languages 

such as C and C++. This can provide benefits to certain classes of applications, 

in the form of reuse of existing code and in some cases increased speed.</p>

<p>The NDK provides:</p>

<ul>

<li>A set of tools and build files used to generate native code libraries from C

files (.apks) that can be deployed on Android devices</li>

<li>A set of native system headers and libraries that will be supported in all

future versions of the Android platform, starting from Android 1.5 </li>

<li>Documentation, samples, and tutorials</li>

</ul>

<p>This release of the NDK release supports the ARMv5TE machine instruction set

and provides stable headers for libc (the C library), libm (the Math library)

and the JNI interface.</p>

<p>This release of the NDK supports the ARMv5TE machine instruction set

and provides stable headers for libc (the C library), libm (the Math library), 

the JNI interface, and other libraries.</p>

<p>Using the NDK may not be relevant for all Android applications. As a

developer, you will need to balance its benefits (faster execution) and its

drawbacks (no portability, JNI overhead, no access to system libraries, and

difficult debugging). Typical good candidates for the NDK are CPU-intensive

operations that don't allocate too much memory, such as signal processing,

physics simulation, custom bytecode/instruction interpreters, and so on.</p>

<p>The NDK will not benefit most applications. As a developer, you will need 

to balance its benefits against its drawbacks; notably, using native code does 

not result in an automatic performance increase, but does always increase 

application complexity. Typical good candidates for the NDK are self-contained,

CPU-intensive operations that don't allocate much memory, such as signal processing,

physics simulation, and so on. Simply re-coding a method to run in C usually does 

not result in a large performance increase. The NDK can, however, can be 

an effective way to reuse a large corpus of existing C/C++ code.</p>

<p>Please note that the NDK <em>does not</em> enable you to develop native-only

applications. Android's primary runtime remains the Dalvik virtual machine.</p>

<ul>

<li>libc (C library) headers</li>

<li>libm (Math library) headers</li>

<li>libm (math library) headers</li>

<li>JNI interface headers</li>

<li>libz (Zlib compression) headers</li>

<li>liblog (Android logging) header</li>

<li>A Minimal set of headers for C++ support</li>

</ul>

<p>The NDK also provides a build system that lets you work efficiently with your

defines the native sources you want to compile</li>

<li>APPLICATION-MK.TXT &mdash; describes the use of the Application.mk file,

which describes the native sources required by your Android application</li>

<li>HOWTO.TXT &mdash; information about common tasks associated with NDK 

development.</li>

<li>SYSTEM-ISSUES.TXT &mdash; known issues in the Android system images 

that you should be aware of, if you are developing using the NDK. </li>

<li>STABLE-APIS.TXT &mdash; a complete list of the stable APIs exposed

by headers in the NDK.</li>

</ul>

<p>Additionally, the package includes detailed information about the "bionic"

C library provided with the Android platform that you should be aware of, if you

are developing using the NDK. You can find the documentation in the 

<code>&lt;ndk&gt;/docs/system/libc/</code> directory:</p>

<ul>

<li>OVERVIEW.TXT &mdash; provides an overview of the "bionic" C library and the 

features it offers.</li>

</ul>

<h4>Sample applications</h4>

<h4>Android platform compatibility</h4>

<ul>

  <li>The native libraries created by the Android NDK can only be used on

devices running the Android 1.5 platform version or later. This is due to subtle

devices running the Android 1.5 platform version or later. This is due to 

toolchain and ABI related changes that make the native libraries incompatible

with 1.0 and 1.1 system images.</li>

  <li>For this reason, you should use native libraries produced with the NDK in

      <li><a href="<?cs var:toroot ?>sdk/android-1.1.html">Android 1.1 Version Notes</a></li>

    </ul>

  </li>

  <li>

    <h2>Native Development Tools</h2>

    <ul>

      <li><a href="<?cs var:toroot ?>sdk/ndk/1.5_r1/index.html">Android 1.5 NDK, r1</a></li>

    </ul>

  </li>

  <li>

    <h2>Previous SDK Releases</h2>

    <ul>