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Merge "Doc change: updating ndk download and overview page" into gingerbread

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Robert Ly
2010-11-30 13:51:05 -08:00
committed by Android (Google) Code Review
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docs/html/sdk/ndk/index.jd
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@@ -67,73 +67,71 @@ padding: .25em 1em;
width="9px" /> Android NDK, Revision 5</a> <em>(November 2010)</em> width="9px" /> Android NDK, Revision 5</a> <em>(November 2010)</em>
<div class="toggleme"> <div class="toggleme">
<dl> <p>This release of the NDK includes many new APIs, most of which are introduced to
<dt>NDK r5 notes:</dt> support the development of games and similar applications that make extensive use
of native code. Using the APIs, developers have direct native access to events, audio,
<dd> graphics and window management, assets, and storage. Developers can also implement the
<p>The r5 release of the NDK includes many new APIs, many of which are introduced to Android application lifecycle in native code with help from the new
support native game development and applications that require similar requirements. Most {@link android.app.NativeActivity} class. For detailed information describing the changes in this
notably, native activities are now supported, which allow you to write an application release, read the CHANGES.HTML document included in the downloaded NDK package.
entirely with native code. For detailed information describing the changes in this </p>
release, read the CHANGES.HTML document included in the downloaded NDK package.</p>
</dd>
</dl>
<dl> <dl>
<dt>General notes:</dt> <dt>General notes:</dt>
<dd> <dd>
<ul> <ul>
<li>Adds support for native activities, which allows you to implement the
<li>A new toolchain (based on GCC 4.4.3), which generates better code, and can also now Android application lifecycle in native code.</li>
be used as a standalone cross-compiler, for people who want to build their stuff with
<code>./configure &amp;&amp; make</code>. See
docs/STANDALONE-TOOLCHAIN.html for the details. The binaries for GCC 4.4.0 are still provided,
but the 4.2.1 binaries were removed.</li>
<li>Support for prebuilt static and shared libraries (docs/PREBUILTS.html), module
exports and imports to make sharing and reuse of third-party modules much easier
(docs/IMPORT-MODULE.html explains why).</li>
<li>A C++ STL implementation (based on STLport) is now provided as a helper module. It
can be used either as a static or shared library (details and usage exemple under
sources/android/stlport/README). <strong>Note:</strong> For now, C++ Exceptions and RTTI are still
not supported.</li>
<li>Improvements to the <code>cpufeatures</code> helper library to deal with buggy
kernel that incorrectly report they run on an ARMv7 CPU (while the device really is an ARMv6). We
recommend developers that use it to simply rebuild their applications to benefit from it, then
upload to Market.</li>
<li>Adds support for native activities, which allows you to write completely native
applications.</li>
<li>Adds an EGL library that lets you create and manage OpenGL ES textures and
services.</li>
<li>Adds native support for the following: <li>Adds native support for the following:
<ul> <ul>
<li>Input subsystem (such as the keyboard and touch screen)</li> <li>Input subsystem (such as the keyboard and touch screen)</li>
<li>Access to sensor data (accelerometer, compass, gyroscope, etc).</li>
<li>Event loop APIs to wait for things such as input and sensor events.</li>
<li>Window and surface subsystem</li> <li>Window and surface subsystem</li>
<li>Audio APIs based on the OpenSL ES standard that support playback and recording <li>Audio APIs based on the OpenSL ES standard that support playback and recording
as well as control over platform audio effects</li> as well as control over platform audio effects</li>
<li>Event loop APIs to wait for things such as input and sensor events</li> <li>Access to assets packaged in an <code>.apk</code> file.</li>
<li>Access to assets packaged in the <code>.apk</code></li>
<li>Access to sensor data (accelerometer, compass, gyroscope, etc.)</li>
</ul> </ul>
</li> </li>
<li>New sample applications, <code>native-plasma</code> and <li>Includes a new toolchain (based on GCC 4.4.3), which generates better code, and can also now
<code>native-activity</code>, to demonstrate how to write a native activity.</li> be used as a standalone cross-compiler, for people who want to build their stuff with
<code>./configure &amp;&amp; make</code>. See
docs/STANDALONE-TOOLCHAIN.html for the details. The binaries for GCC 4.4.0 are still provided,
but the 4.2.1 binaries were removed.</li>
<li>Plus many bugfixes and other small improvements; see docs/CHANGES.html for a more <li>Adds support for prebuilt static and shared libraries (docs/PREBUILTS.html) and module
detailed list of changes.</li> exports and imports to make sharing and reuse of third-party modules much easier
(docs/IMPORT-MODULE.html explains why).</li>
<li>Provides a default C++ STL implementation (based on STLport) as a helper module. It can be used either
as a static or shared library (details and usage examples are in sources/android/stlport/README). Prebuilt
binaries for STLport (static or shared) and GNU libstdc++ (static only) are also provided if you choose to
compile against those libraries instead of the default C++ STL implementation.
C++ Exceptions and RTTI are not supported in the default STL implementation. For more information, see
docs/CPLUSPLUS-SUPPORT.HTML.</li>
<li>Includes improvements to the <code>cpufeatures</code> helper library that improves reporting
of the CPU type (some devices previously reported ARMv7 CPU when the device really was an ARMv6). We
recommend developers that use this library to rebuild their applications then
upload to Market to benefit from the improvements.</li>
<li>Adds an EGL library that lets you create and manage OpenGL ES textures and
services.</li>
<li>Adds new sample applications, <code>native-plasma</code> and <code>native-activity</code>,
to demonstrate how to write a native activity.</li>
<li>Includes many bugfixes and other small improvements; see docs/CHANGES.html for a more
detailed list of changes.</li>
</ul> </ul>
</dd> </dd>
</dl> </dl>
@@ -296,14 +294,13 @@ detailed list of changes.</li>
<h2 id="installing">Installing the NDK</h2> <h2 id="installing">Installing the NDK</h2>
<p>Installing the NDK on your development computer is straightforward and involves extracting the <p>Installing the NDK on your development computer is straightforward and involves extracting the
NDK from its download package. Unlike previous releases, there is no need to run a host-setup NDK from its download package.</p>
script.</p>
<p>Before you get started make sure that you have downloaded the latest <a href= <p>Before you get started make sure that you have downloaded the latest <a href=
"{@docRoot}sdk/index.html">Android SDK</a> and upgraded your applications and environment as "{@docRoot}sdk/index.html">Android SDK</a> and upgraded your applications and environment as
needed. The NDK will not work with older versions of the Android SDK. Also, take a moment to needed. The NDK is compatible with older platform versions but not older versions of the SDK tools.
review the <a href="{@docRoot}sdk/ndk/reqs.html">System and Software Requirements</a> for the Also, take a moment to review the <a href="{@docRoot}sdk/ndk/reqs.html">System and Software Requirements</a>
NDK, if you haven't already.</p> for the NDK, if you haven't already.</p>
<p>To install the NDK, follow these steps:</p> <p>To install the NDK, follow these steps:</p>
@@ -318,7 +315,7 @@ detailed list of changes.</li>
<code>&lt;ndk&gt;</code>.</li> <code>&lt;ndk&gt;</code>.</li>
</ol> </ol>
<p>You are now ready start working with the NDK.</p> <p>You are now ready to start working with the NDK.</p>
<h2 id="gettingstarted">Getting Started with the NDK</h2> <h2 id="gettingstarted">Getting Started with the NDK</h2>
@@ -342,8 +339,7 @@ detailed list of changes.</li>
<li>Build your native code by running the 'ndk-build' script from your project's directory. It <li>Build your native code by running the 'ndk-build' script from your project's directory. It
is located in the top-level NDK directory: is located in the top-level NDK directory:
<pre class="no-pretty-print"> <pre class="no-pretty-print">cd &lt;project&gt;
cd &lt;project&gt;
&lt;ndk&gt;/ndk-build &lt;ndk&gt;/ndk-build
</pre> </pre>
@@ -360,219 +356,9 @@ cd &lt;project&gt;
<h2 id="samples">Sample Applications</h2> <h2 id="samples">Sample Applications</h2>
<p>The NDK includes sample applications that illustrate how to use native code in your Android <p>The NDK includes sample Android applications that illustrate how to use native code in your
applications:</p> Android applications. For more information, see <a href=
"{@docRoot}sdk/ndk/overview.html#samples">Sample Applications</a>.</p>
<ul>
<li><code>hello-jni</code> &mdash; a simple application that loads a string from a native
method implemented in a shared library and then displays it in the application UI.</li>
<li><code>two-libs</code> &mdash; a simple application that loads a shared library dynamically
and calls a native method provided by the library. In this case, the method is implemented in a
static library imported by the shared library.</li>
<li><code>san-angeles</code> &mdash; a simple application that renders 3D graphics through the
native OpenGL ES APIs, while managing activity lifecycle with a {@link
android.opengl.GLSurfaceView} object.</li>
<li><code>hello-gl2</code> &mdash; a simple application that renders a triangle using OpenGL ES
2.0 vertex and fragment shaders.</li>
<li><code>hello-neon</code> &mdash; a simple application that shows how to use the
<code>cpufeatures</code> library to check CPU capabilities at runtime, then use NEON intrinsics
if supported by the CPU. Specifically, the application implements two versions of a tiny
benchmark for a FIR filter loop, a C version and a NEON-optimized version for devices that
support it.</li>
<li><code>bitmap-plasma</code> &mdash; a simple application that demonstrates how to access the
pixel buffers of Android {@link android.graphics.Bitmap} objects from native code, and uses
this to generate an old-school "plasma" effect.</li>
<li><code>native-activity</code> &mdash; a simple application that demonstrates how to use the
native-app-glue static library to create a native activity</li>
<li><code>native-plasma</code> &mdash; a version of bitmap-plasma implemented with a native
activity.</li>
</ul>
<p>For each sample, the NDK includes the corresponding C source code and the necessary Android.mk
and Application.mk files. There are located under <code>&lt;ndk&gt;/samples/&lt;name&gt;/</code>
and their source code can be found under <code>&lt;ndk&gt;/samples/&lt;name&gt;/jni/</code>.</p>
<p>You can build the shared libraries for the sample apps by going into
<code>&lt;ndk&gt;/samples/&lt;name&gt;/</code> then calling the <code>ndk-build</code> command.
The generated shared libraries will be located under
<code>&lt;ndk&gt;/samples/&lt;name&gt;/libs/armeabi/</code> for (ARMv5TE machine code) and/or
<code>&lt;ndk&gt;/samples/&lt;name&gt;/libs/armeabi-v7a/</code> for (ARMv7 machine code).</p>
<p>Next, build the sample Android applications that use the shared libraries:</p>
<ul>
<li>If you are developing in Eclipse with ADT, use the New Project Wizard to create a new
Android project for each sample, using the "Import from Existing Source" option and importing
the source from <code>&lt;ndk&gt;/apps/&lt;app_name&gt;/project/</code>. Then, set up an AVD,
if necessary, and build/run the application in the emulator. For more information about
creating a new Android project in Eclipse, see <a href=
"{@docRoot}guide/developing/eclipse-adt.html">Developing in Eclipse</a>.</li>
<li>If you are developing with Ant, use the <code>android</code> tool to create the build file
for each of the sample projects at <code>&lt;ndk&gt;/apps/&lt;app_name&gt;/project/</code>.
Then set up an AVD, if necessary, build your project in the usual way, and run it in the
emulator. For more information, see <a href=
"{@docRoot}guide/developing/other-ide.html">Developing in Other IDEs</a>.</li>
</ul>
<h3 id="hello-jni">Exploring the hello-jni Sample</h3>
<p>The hello-jni sample is a simple demonstration on how to use JNI from an Android application.
The HelloJni activity receives a string from a simple C function and displays it in a
TextView.</p>
<p>The main components of the sample include:</p>
<ul>
<li>The familiar basic structure of an Android application (an <code>AndroidManifest.xml</code>
file, a <code>src/</code> and <code>res</code> directories, and a main activity)</li>
<li>A <code>jni/</code> directory that includes the implemented source file for the native code
as well as the Android.mk file</li>
<li>A <code>tests/</code> directory that contains unit test code.</li>
</ul>
<ol>
<li>Create a new project in Eclipse from the existing sample source or use the
<code>android</code> tool to update the project so it generates a build.xml file that you can
use to build the sample.
<ul>
<li>In Eclipse:
<ol type="a">
<li>Click <strong>File &gt; New Android Project...</strong></li>
<li>Select the <strong>Create project from existing source</strong> radio button.</li>
<li>Select any API level above Android 1.5.</li>
<li>In the <strong>Location</strong> field, click <strong>Browse...</strong> and select
the <code>&lt;ndk-root&gt;/samples/hello-jni</code> directory.</li>
<li>Click <strong>Finish</strong>.</li>
</ol>
</li>
<li>On the command line:
<ol type="a">
<li>Change to the <code>&lt;ndk-root&gt;/samples/hello-jni</code> directory.</li>
<li>Run the following command to generate a build.xml file:
<pre class="no-pretty-print">
android update project -p . -s
</pre>
</li>
</ol>
</li>
</ul>
</li>
<li>Compile the native code using the <code>ndk-build</code> command.
<pre class="no-pretty-print">
cd &lt;ndk-root&gt;/samples/hello-jni
&lt;ndk_root&gt;/ndk-build
</pre>
</li>
<li>Build and install the application as you would a normal Android application. If you are
using Eclipse, run the application to build and install it on a device. If you are using Ant,
run the following commands from the project directory:
<pre class="no-pretty-print">
ant debug
adb install bin/HelloJni-debug.apk
</pre>
</li>
</ol>
<p>When you run the application on the device, the string <code>Hello JNI</code> should appear on
your device. You can explore the rest of the samples that are located in the
<code>&lt;ndk-root&gt;/samples</code> directory for more examples on how to use the JNI.</p>
<h3 id="native-activity">Exploring the native-activity Sample Application</h3>
<p>The native-activity sample provided with the Android NDK demonstrates how to use the
android_native_app_glue static library. This static library makes creating a native activity
easier by providing you with an implementation that handles your callbacks in another thread, so
you do not have to worry about them blocking your main UI thread. The main parts of the sample
are described below:</p>
<ul>
<li>The familiar basic structure of an Android application (an <code>AndroidManifest.xml</code>
file, a <code>src/</code> and <code>res</code> directories). The AndroidManifest.xml declares
that the application is native and specifies the .so file of the native activity. See {@link
android.app.NativeActivity} for the source or see the
<code>&lt;ndk_root&gt;/platforms/samples/native-activity/AndroidManifest.xml</code> file.</li>
<li>A <code>jni/</code> directory contains the native activity, main.c, which uses the
<code>android_native_app_glue.h</code> interface to implement the activity. The Android.mk that
describes the native module to the build system also exists here.</li>
</ul>
<p>To build this sample application:</p>
<ol>
<li>Create a new project in Eclipse from the existing sample source or use the
<code>android</code> tool to update the project so it generates a build.xml file that you can
use to build the sample.
<ul>
<li>In Eclipse:
<ol type="a">
<li>Click <strong>File &gt; New Android Project...</strong></li>
<li>Select the <strong>Create project from existing source</strong> radio button.</li>
<li>Select any API level above Android 2.3.</li>
<li>In the <strong>Location</strong> field, click <strong>Browse...</strong> and select
the <code>&lt;ndk-root&gt;/samples/native-activity</code> directory.</li>
<li>Click <strong>Finish</strong>.</li>
</ol>
</li>
<li>On the command line:
<ol type="a">
<li>Change to the <code>&lt;ndk-root&gt;/samples/native-activity</code> directory.</li>
<li>Run the following command to generate a build.xml file:
<pre class="no-pretty-print">
android update project -p . -s
</pre>
</li>
</ol>
</li>
</ul>
</li>
<li>Compile the native code using the <code>ndk-build</code> command.
<pre class="no-pretty-print">
cd &lt;ndk-root&gt;/platforms/samples/android-9/samples/native-activity
&lt;ndk_root&gt;/ndk-build
</pre>
</li>
<li>Build and install the application as you would a normal Android application. If you are
using Eclipse, run the application to build and install it on a device. If you are using Ant,
run the following commands in the project directory, then run the application on the device:
<pre class="no-pretty-print">
ant debug
adb install bin/NativeActivity-debug.apk
</pre>
</li>
</ol>
<h2 id="forum">Discussion Forum and Mailing List</h2> <h2 id="forum">Discussion Forum and Mailing List</h2>

267
docs/html/sdk/ndk/overview.jd
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@@ -7,10 +7,8 @@ page.title=What is the NDK?
<ol> <ol>
<li><a href="#choosing">When to Develop in Native Code</a></li> <li><a href="#choosing">When to Develop in Native Code</a></li>
<li> <li>
<a href="#contents">Contents of the NDK</a> <a href="#contents">Contents of the NDK</a>
<ol> <ol>
<li><a href="#tools">Development tools</a></li> <li><a href="#tools">Development tools</a></li>
@@ -19,9 +17,7 @@ page.title=What is the NDK?
<li><a href="#samples">Sample applications</a></li> <li><a href="#samples">Sample applications</a></li>
</ol> </ol>
</li> </li>
<li><a href="#reqs">System and Software Requirements</a></li> <li><a href="#reqs">System and Software Requirements</a></li>
</ol> </ol>
</div> </div>
</div> </div>
@@ -102,9 +98,8 @@ page.title=What is the NDK?
later.</li> later.</li>
<li> <li>
<p>Write a native activity, which allows you to potentially create an application completely in native <p>Write a native activity, which allows you to implement the lifecycle callbacks in native
code, because you can implement the lifecycle callbacks natively. The Android SDK provides code. The Android SDK provides the {@link android.app.NativeActivity} class, which is a convenience class that notifies your
the {@link android.app.NativeActivity} class, which is a convenience class that notifies your
native code of any activity lifecycle callbacks (<code>onCreate()</code>, <code>onPause()</code>, native code of any activity lifecycle callbacks (<code>onCreate()</code>, <code>onPause()</code>,
<code>onResume()</code>, etc). You can implement the callbacks in your native code to handle <code>onResume()</code>, etc). You can implement the callbacks in your native code to handle
these events when they occur. Applications that use native activities must be run on Android these events when they occur. Applications that use native activities must be run on Android
@@ -142,6 +137,10 @@ page.title=What is the NDK?
<li>libjnigraphics (Pixel buffer access) header (for Android 2.2 and above).</li> <li>libjnigraphics (Pixel buffer access) header (for Android 2.2 and above).</li>
<li>A Minimal set of headers for C++ support</li> <li>A Minimal set of headers for C++ support</li>
<li>OpenSL ES native audio libraries</li>
<li>Android native application APIS</li>
</ul> </ul>
<p>The NDK also provides a build system that lets you work efficiently with your sources, without <p>The NDK also provides a build system that lets you work efficiently with your sources, without
@@ -163,7 +162,8 @@ page.title=What is the NDK?
the <code>&lt;ndk&gt;/docs/</code> directory. Included are these files:</p> the <code>&lt;ndk&gt;/docs/</code> directory. Included are these files:</p>
<ul> <ul>
<li>INSTALL.HTML &mdash; describes how to install the NDK and configure it for your host <li>
INSTALL.HTML &mdash; describes how to install the NDK and configure it for your host
system</li> system</li>
<li>OVERVIEW.HTML &mdash; provides an overview of the NDK capabilities and usage</li> <li>OVERVIEW.HTML &mdash; provides an overview of the NDK capabilities and usage</li>
@@ -173,15 +173,7 @@ page.title=What is the NDK?
<li>APPLICATION-MK.HTML &mdash; describes the use of the Application.mk file, which describes <li>APPLICATION-MK.HTML &mdash; describes the use of the Application.mk file, which describes
the native sources required by your Android application</li> the native sources required by your Android application</li>
<li>CPLUSPLUS-SUPPORT.HTML &mdash; describes the C++ support provided in the Android NDK</li>
<li>HOWTO.HTML &mdash; information about common tasks associated with NDK development.</li>
<li>SYSTEM-ISSUES.HTML &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.HTML &mdash; a complete list of the stable APIs exposed by headers in the
NDK.</li>
<li>CPU-ARCH-ABIS.HTML &mdash; a description of supported CPU architectures and how to target <li>CPU-ARCH-ABIS.HTML &mdash; a description of supported CPU architectures and how to target
them.</li> them.</li>
@@ -193,6 +185,32 @@ page.title=What is the NDK?
instructions.</li> instructions.</li>
<li>CHANGES.HTML &mdash; a complete list of changes to the NDK across all releases.</li> <li>CHANGES.HTML &mdash; a complete list of changes to the NDK across all releases.</li>
<li>DEVELOPMENT.HTML &mdash; describes how to modify the NDK and generate release packages for it</li>
<li>HOWTO.HTML &mdash; information about common tasks associated with NDK development</li>
<li>IMPORT-MODULE.HTML &mdash; describes how to share and reuse modules</li>
<li>LICENSES.HTML &mdash; information about the various open source licenses that govern the Android NDK</li>
<li>NATIVE-ACTIVITY.HTML &mdash; describes how to implement native activities</li>
<li>NDK-BUILD.HTML &mdash; describes the usage of the ndk-build script</li>
<li>NDK-GDB.HTML &mdash; describes how to use the native code debugger</li>
<li>PREBUILTS.HTML &mdash; information about how shared and static prebuilt libraries work </li>
<li>STANDALONE-TOOLCHAIN.HTML &mdash; describes how to use Android NDK toolchain as a standalone
compiler (still in beta).</li>
<li>SYSTEM-ISSUES.HTML &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.HTML &mdash; a complete list of the stable APIs exposed by headers in the
NDK.</li>
</ul> </ul>
<p>Additionally, the package includes detailed information about the "bionic" C library provided <p>Additionally, the package includes detailed information about the "bionic" C library provided
@@ -206,9 +224,218 @@ page.title=What is the NDK?
<h3 id="samples">Sample applications</h3> <h3 id="samples">Sample applications</h3>
<p>The NDK includes sample Android applications that illustrate how to use native code in your <p>The NDK includes sample applications that illustrate how to use native code in your Android
Android applications. For more information, see <a href= applications:</p>
"{@docRoot}sdk/ndk/installing.html#samples">Sample Applications</a>.</p>
<ul>
<li><code>hello-jni</code> &mdash; a simple application that loads a string from a native
method implemented in a shared library and then displays it in the application UI.</li>
<li><code>two-libs</code> &mdash; a simple application that loads a shared library dynamically
and calls a native method provided by the library. In this case, the method is implemented in a
static library imported by the shared library.</li>
<li><code>san-angeles</code> &mdash; a simple application that renders 3D graphics through the
native OpenGL ES APIs, while managing activity lifecycle with a {@link
android.opengl.GLSurfaceView} object.</li>
<li><code>hello-gl2</code> &mdash; a simple application that renders a triangle using OpenGL ES
2.0 vertex and fragment shaders.</li>
<li><code>hello-neon</code> &mdash; a simple application that shows how to use the
<code>cpufeatures</code> library to check CPU capabilities at runtime, then use NEON intrinsics
if supported by the CPU. Specifically, the application implements two versions of a tiny
benchmark for a FIR filter loop, a C version and a NEON-optimized version for devices that
support it.</li>
<li><code>bitmap-plasma</code> &mdash; a simple application that demonstrates how to access the
pixel buffers of Android {@link android.graphics.Bitmap} objects from native code, and uses
this to generate an old-school "plasma" effect.</li>
<li><code>native-activity</code> &mdash; a simple application that demonstrates how to use the
native-app-glue static library to create a native activity</li>
<li><code>native-plasma</code> &mdash; a version of bitmap-plasma implemented with a native
activity.</li>
</ul>
<p>For each sample, the NDK includes the corresponding C source code and the necessary Android.mk
and Application.mk files. There are located under <code>&lt;ndk&gt;/samples/&lt;name&gt;/</code>
and their source code can be found under <code>&lt;ndk&gt;/samples/&lt;name&gt;/jni/</code>.</p>
<p>You can build the shared libraries for the sample apps by going into
<code>&lt;ndk&gt;/samples/&lt;name&gt;/</code> then calling the <code>ndk-build</code> command.
The generated shared libraries will be located under
<code>&lt;ndk&gt;/samples/&lt;name&gt;/libs/armeabi/</code> for (ARMv5TE machine code) and/or
<code>&lt;ndk&gt;/samples/&lt;name&gt;/libs/armeabi-v7a/</code> for (ARMv7 machine code).</p>
<p>Next, build the sample Android applications that use the shared libraries:</p>
<ul>
<li>If you are developing in Eclipse with ADT, use the New Project Wizard to create a new
Android project for each sample, using the "Import from Existing Source" option and importing
the source from <code>&lt;ndk&gt;/apps/&lt;app_name&gt;/project/</code>. Then, set up an AVD,
if necessary, and build/run the application in the emulator. For more information about
creating a new Android project in Eclipse, see <a href=
"{@docRoot}guide/developing/eclipse-adt.html">Developing in Eclipse</a>.</li>
<li>If you are developing with Ant, use the <code>android</code> tool to create the build file
for each of the sample projects at <code>&lt;ndk&gt;/apps/&lt;app_name&gt;/project/</code>.
Then set up an AVD, if necessary, build your project in the usual way, and run it in the
emulator. For more information, see <a href=
"{@docRoot}guide/developing/other-ide.html">Developing in Other IDEs</a>.</li>
</ul>
<h4 id="hello-jni">Exploring the hello-jni Sample</h4>
<p>The hello-jni sample is a simple demonstration on how to use JNI from an Android application.
The HelloJni activity receives a string from a simple C function and displays it in a
TextView.</p>
<p>The main components of the sample include:</p>
<ul>
<li>The familiar basic structure of an Android application (an <code>AndroidManifest.xml</code>
file, a <code>src/</code> and <code>res</code> directories, and a main activity)</li>
<li>A <code>jni/</code> directory that includes the implemented source file for the native code
as well as the Android.mk file</li>
<li>A <code>tests/</code> directory that contains unit test code.</li>
</ul>
<ol>
<li>Create a new project in Eclipse from the existing sample source or use the
<code>android</code> tool to update the project so it generates a build.xml file that you can
use to build the sample.
<ul>
<li>In Eclipse:
<ol type="a">
<li>Click <strong>File &gt; New Android Project...</strong></li>
<li>Select the <strong>Create project from existing source</strong> radio button.</li>
<li>Select any API level above Android 1.5.</li>
<li>In the <strong>Location</strong> field, click <strong>Browse...</strong> and select
the <code>&lt;ndk-root&gt;/samples/hello-jni</code> directory.</li>
<li>Click <strong>Finish</strong>.</li>
</ol>
</li>
<li>On the command line:
<ol type="a">
<li>Change to the <code>&lt;ndk-root&gt;/samples/hello-jni</code> directory.</li>
<li>Run the following command to generate a build.xml file:
<pre class="no-pretty-print">android update project -p . -s</pre>
</li>
</ol>
</li>
</ul>
</li>
<li>Compile the native code using the <code>ndk-build</code> command.
<pre class="no-pretty-print">
cd &lt;ndk-root&gt;/samples/hello-jni
&lt;ndk_root&gt;/ndk-build
</pre>
</li>
<li>Build and install the application as you would a normal Android application. If you are
using Eclipse, run the application to build and install it on a device. If you are using Ant,
run the following commands from the project directory:
<pre class="no-pretty-print">
ant debug
adb install bin/HelloJni-debug.apk
</pre>
</li>
</ol>
<p>When you run the application on the device, the string <code>Hello JNI</code> should appear on
your device. You can explore the rest of the samples that are located in the
<code>&lt;ndk-root&gt;/samples</code> directory for more examples on how to use the JNI.</p>
<h4 id="native-activity">Exploring the native-activity Sample Application</h4>
<p>The native-activity sample provided with the Android NDK demonstrates how to use the
android_native_app_glue static library. This static library makes creating a native activity
easier by providing you with an implementation that handles your callbacks in another thread, so
you do not have to worry about them blocking your main UI thread. The main parts of the sample
are described below:</p>
<ul>
<li>The familiar basic structure of an Android application (an <code>AndroidManifest.xml</code>
file, a <code>src/</code> and <code>res</code> directories). The AndroidManifest.xml declares
that the application is native and specifies the .so file of the native activity. See {@link
android.app.NativeActivity} for the source or see the
<code>&lt;ndk_root&gt;/platforms/samples/native-activity/AndroidManifest.xml</code> file.</li>
<li>A <code>jni/</code> directory contains the native activity, main.c, which uses the
<code>android_native_app_glue.h</code> interface to implement the activity. The Android.mk that
describes the native module to the build system also exists here.</li>
</ul>
<p>To build this sample application:</p>
<ol>
<li>Create a new project in Eclipse from the existing sample source or use the
<code>android</code> tool to update the project so it generates a build.xml file that you can
use to build the sample.
<ul>
<li>In Eclipse:
<ol type="a">
<li>Click <strong>File &gt; New Android Project...</strong></li>
<li>Select the <strong>Create project from existing source</strong> radio button.</li>
<li>Select any API level above Android 2.3.</li>
<li>In the <strong>Location</strong> field, click <strong>Browse...</strong> and select
the <code>&lt;ndk-root&gt;/samples/native-activity</code> directory.</li>
<li>Click <strong>Finish</strong>.</li>
</ol>
</li>
<li>On the command line:
<ol type="a">
<li>Change to the <code>&lt;ndk-root&gt;/samples/native-activity</code> directory.</li>
<li>Run the following command to generate a build.xml file:
<pre class="no-pretty-print">
android update project -p . -s
</pre>
</li>
</ol>
</li>
</ul>
</li>
<li>Compile the native code using the <code>ndk-build</code> command.
<pre class="no-pretty-print">
cd &lt;ndk-root&gt;/platforms/samples/android-9/samples/native-activity
&lt;ndk_root&gt;/ndk-build
</pre>
</li>
<li>Build and install the application as you would a normal Android application. If you are
using Eclipse, run the application to build and install it on a device. If you are using Ant,
run the following commands in the project directory, then run the application on the device:
<pre class="no-pretty-print">
ant debug
adb install bin/NativeActivity-debug.apk
</pre>
</li>
</ol>
<h2 id="reqs">System and Software Requirements</h2> <h2 id="reqs">System and Software Requirements</h2>