docs/html/tools/studio/index.jd

page.title=Android Studio Overview
page.image=images/cards/card-android-studio-overview_16x9_2x.jpg
page.metaDescription=Learn about the official IDE for Android.
page.tags=studio,sdk,tools,firstapp
@jd:body

<div id="qv-wrapper">
<div id="qv">

    <h2>In this document</h2>
    <ol>
      <li><a href="#project-structure">Project and File Structure</a></li>
      <li><a href="#build-system">Android Build System</a></li>
      <li><a href="#debug-perf">Debug and Performance</a></li>


    </ol>

  <h2>See also</h2>
  <ol>
    <li><a class="external-link" href="http://confluence.jetbrains.com/display/IntelliJIDEA/FAQ+on+Migrating+to+IntelliJ+IDEA">IntelliJ FAQ on migrating to IntelliJ IDEA</a></li>
  </ol>

</div>
</div>


<p>Android Studio is the official IDE for Android application development,
based on <a class="external-link" href="https://www.jetbrains.com/idea/" target="_blank">IntelliJ IDEA</a>.
On top of the capabilities you expect from IntelliJ,
Android Studio offers:</p>

<ul>
  <li>Flexible Gradle-based build system</li>
  <li>Build variants and multiple <code>apk</code> file generation</li>
  <li>Code templates to help you build common app features</li>
  <li>Rich layout editor with support for drag and drop theme editing</li>
  <li>{@code lint} tools to catch performance, usability, version compatibility, and other problems</li>
  <li>ProGuard and app-signing capabilities</li>
  <li>Built-in support for
  <a href="http://developers.google.com/cloud/devtools/android_studio_templates/">Google Cloud Platform</a>,
  making it easy to integrate Google Cloud Messaging and App Engine</li>
  <li>And much more</li>
</ul>


<p>If you're new to Android Studio or the IntelliJ IDEA interface, this
page provides an introduction to some key Android
Studio features.</p>

<p>For specific Android Studio how-to documentation, see the pages in the <a href=
"{@docRoot}tools/workflow/index.html">Workflow</a> section, such as <a href=
"{@docRoot}tools/projects/projects-studio.html">Managing Projects from Android Studio</a> and
<a href="{@docRoot}tools/building/building-studio.html">Building and Running from Android
Studio</a>. For a summary of the latest changes to Android Studio, see the
<a href="{@docRoot}tools/revisions/studio.html">Android Studio Release Notes</a>.</p>




<h2 id="project-structure">Project and File Structure</h2>

<h3 id="project-view"><em>Android</em> project view</h3>
<p>By default, Android Studio displays your project files in the <em>Android</em> project view. This
view shows a flattened version of your project's structure that provides quick access to the key
source files of Android projects and helps you work with the
<a href="{@docRoot}sdk/installing/studio-build.html">Gradle-based build system</a>.
The <em>Android</em> project view:</p>

<ul>
  <li>Shows the most important source directories at the top level of the module hierarchy.</li>
  <li>Groups the build files for all modules in a common folder.</li>
  <li>Groups all the manifest files for each module in a common folder.</li>
  <li>Shows resource files from all Gradle source sets.</li>
  <li>Groups resource files for different locales, orientations, and screen types in a single
  group per resource type.</li>
</ul>

     <img src="{@docRoot}images/tools/projectview01.png" />
     <p class="img-caption"><strong>Figure 1.</strong> Show the Android project view.</p>
     <img src="{@docRoot}images/tools/studio-projectview_scripts.png"  />
     <p class="img-caption"><strong>Figure 2.</strong> Show project build files.</p>

<p>The <em>Android</em> project view shows all the build files at the top level of the project
hierarchy under <strong>Gradle Scripts</strong>. Each project module appears as a folder at the
top level of the project hierarchy and contains these four elements at the top level:</p>

<ul>
  <li><code>java/</code> - Source files for the module.</li>
  <li><code>manifests/</code> - Manifest files for the module.</li>
  <li><code>res/</code> - Resource files for the module.</li>
  <li><code>Gradle Scripts/</code> - Gradle build and property files.</li>
</ul>

<p>For example, <em>Android</em> project view groups all the instances of the
<code>ic_launcher.png</code> resource for different screen densities under the same element.</p>

<p class="note"><strong>Note:</strong> The project structure on disk differs from this flattened
representation. To switch to back to the segregated project view, select <strong>Project</strong>
from the <strong>Project</strong> drop-down. </p>



<h3 id="other-views">Other Android Studio views</h3>
<p>When you use the <em>Project</em> view in Android Studio, you
should notice that the project structure appears different than you may be used to in Eclipse. Each
instance of Android Studio contains a project with one or more application modules. Each
application module folder contains the complete source sets for that module, including
{@code src/main/} and {@code src/androidTest/} directories, resources, build
file and the Android manifest. For the most part, you will need to modify the files under each
module's {@code src/main/} directory for source code updates, the gradle.build file for build
specification and the files under {@code src/androidTest/} directory for test case creation.

    <p>  <img src="{@docRoot}images/tools/studio-project-layout.png" alt="" /></p>
    <p>  <class="img-caption"><strong>Figure 3.</strong> View Android Studio <em>Project</em>
         structure.</p>

<p>You can also customize the view of the project files to focus on specific aspects of your app
development: </p>

<ul>
  <li><em>Packages</em> </li>
  <li><em>Project Files</em> </li>
  <li><em>Scratches</em> </li>
  <li><em>Problems</em> </li>
  <li><em>Production</em> </li>
  <li><em>Tests</em> </li>
</ul>

<p>For example, selecting the <strong>Problems</strong> view of your project displays links to the
source files containing any recognized coding and syntax errors, such as missing an XML element
closing tag in a layout file.<p>

<p>For more information, see
<a class="external-link" href="http://confluence.jetbrains.com/display/IntelliJIDEA/Project+Organization">IntelliJ project organization</a>
and <a href="{@docRoot}tools/projects/index.html">Managing Projects</a>.</p>



<h2 id="build-system">Android Build System</h2>
<p>The Android build system is the toolkit you use to build, test, run and package
your apps. This build system replaces the Ant system used with Eclipse ADT. It can run as an
integrated tool from the Android Studio menu and independently from the command line. You can use
the features of the build system to:</p>

<ul>
    <li>Customize, configure, and extend the build process.</li>
    <li>Create multiple APKs for your app with different features using the same project and
    modules.</li>
    <li>Reuse code and resources across source sets.</li>
</ul>

<p>The flexibility of the Android build system enables you to achieve all of this without
modifying your app's core source files. To build an Android Studio project, see
<a href="{@docRoot}tools/building/building-studio.html">Building and Running from Android Studio</a>.
To configure custom build settings in an Android Studio project, see
<a href="{@docRoot}tools/building/configuring-gradle.html">Configuring Gradle Builds</a>.</p>



<h2 id="debug-perf">Debug and Performance</h2>
<p>Android Studio provides a number of improvements to assist you in debugging and improving the
performance of your code, including an improved virtual device management, inline debugging, and
performance analysis tools.</p>

<h3>Android Virtual Device (AVD) Manager</h3>
<p>AVD Manager has updated screens with links to help you select the most popular device
configurations, screen sizes and resolutions for your app previews.</p>
Click the <strong>Android Virtual Device Manager</strong>
<img src="{@docRoot}images/tools/avd-manager-studio.png"
style="vertical-align:bottom;margin:0;height:19px" /> in the toolbar to open it and create
new virtual devices for running your app in the emulator.</p>

<p>The AVD Manager comes with emulators for Nexus 6 and Nexus 9 devices and also supports
creating custom Android device skins based on specific emulator properties and assigning those
skins to hardware profiles. Android Studio installs the Intel&#174; x86 Hardware Accelerated Execution
Manager (HAXM) emulator accelerator and creates a default emulator for quick app prototyping.</p>

<p>For more information, see <a href="{@docRoot}tools/devices/managing-avds.html">Managing AVDs</a>.</p>


<h3 id="inline-debug">Inline debugging</h3>
<p>Use inline debugging to enhance your code walk-throughs in the debugger view
with inline verification of references, expressions, and variable values. Inline debug information
includes: </p>
<ul>
 <li>Inline variable values</li>
 <li>Referring objects that reference a selected object </li>
 <li>Method return values</li>
 <li>Lambda and operator expressions</li>
 <li>Tool tip values</li>
</ul>

<p>To enable inline debugging, in the <em>Debug</em> window click the Settings icon
<img src="{@docRoot}images/tools/studio-debug-settings-icon.png"/> and select the
check box for <strong>Show Values In Editor</strong>.</p>

<h3 id="mem-cpu">Memory and CPU monitor</h3>
<p>Android Studio provides a memory and CPU monitor view so you can more easily monitor your
app's performance and memory usage to track CPU usage, find deallocated objects, locate memory
leaks, and track the amount of memory the connected device is using. With your app running on a
device or emulator, click the <strong>Android</strong> tab in the lower left corner of the
runtime window to launch the Android runtime window. Click the <strong>Memory</strong> or
<strong>CPU</strong> tab. </p>

<img src="{@docRoot}images/tools/studio-memory-monitor.png" srcset="{@docRoot}images/tools/studio-memory-monitor_2x.png 2x" width"635" height="171" alt="" />
    <p class="img-caption"><strong>Figure 4.</strong> Monitor memory and CPU usage.</p>


<h3>Data file access</h3>
<p>The Android SDK tools, such as <a href="{@docRoot}tools/help/systrace.html">Systrace</a>,
<a href="{@docRoot}tools/help/logcat.html">logcat</a>, and
<a href="{@docRoot}tools/help/traceview.html">Traceview</a>, generate performance and debugging
data for detailed app analysis.</p>

<p>To view the available generated data files, click <strong>Captures</strong> in the left
corner of the runtime window. In the list of the generated files, double-click a file to view
the data. Right-click any <code>.hprof</code> files to convert them to a standard
<a href="{@docRoot}tools/help/hprof-conv.html"><code>.hprof</code> </a> file format.</p>


<h3>Code inspections</h3>
<p>In Android Studio, the configured <a href="{@docRoot}tools/help/lint.html"><code>lint</code></a>
and other IDE inspections run automatically whenever you compile your program. In addition to the
configured {@code lint} checks, additional
<a class="external-link" href="https://www.jetbrains.com/idea/help/inspection-basics.html?search=inspection"
target="_blank">IntelliJ code inspections</a> and annotation validation run to streamline code
review.</p>


<p>Android Studio enables several <code>lint</code> checks
to ensure:
<ul>
  <li><code> Cipher.getInstance()</code> is used with safe values</li>
  <li>In custom Views, the associated declare-styleable for the custom view uses the same
  base name as the class name</li>
  <li>Security check for fragment injection</li>
  <li>Where ever property assignment no longer works as expected</li>
  <li>Gradle plugin version is compatible with the SDK</li>
  <li>Right to left validation </li>
  <li>Required API version</li>
  <li>many others</li>
</ul>


<p>Hovering over an inspection error displays the full issue explanation inline for easy error
resolution. There is also a helpful hyperlink at the end of the error message for additional
error information.</p>

<p>With Android Studio, you can also run {@code lint} inspections for a specific build variant, or
for all build variants. You can configure the {@code lint} inspections that run by adding a
<code>lintOptions</code> property to the Android settings in the <code>build.gradle</code>
file.  </p>

<pre>
android {
    lintOptions {
       // set to true to turn off analysis progress reporting by lint
       quiet true
       // if true, stop the gradle build if errors are found
       abortOnError false
       // if true, only report errors
       ignoreWarnings true
    }
</pre>


<p>You can also manage inspection profiles and configure inspections within Android Studio.
Choose <strong>File &gt; Settings &gt;</strong>, expand the <strong>Editor</strong> options,
and select <strong>Inspections</strong>.
The <em>Inspection Configuration</em> page appears with the supported inspections.</p>
<p><img src="{@docRoot}images/tools/studio-inspections-config.png" alt="" /> </p>
<p class="img-caption"><strong>Figure 5.</strong> Configure inspections.</p>

<p class="note"><strong>Note:</strong> To change the behavior of specific
inspection notifications, change the inspection severity, for example from <em>warning</em>
to <em>error</em>. </p>


<p>To manually run inspections in Android Studio, choose <strong>Analyze &gt; Inspect Code</strong>.
The <em>Inspections Scope</em> dialog appears so you can specify the desired inspection profile and scope.</p>



<h4>Running inspections from the command line</h4>
<p>You can also run {@code lint} inspections from the command line in your SDK directory. </p>
<pre>
sdk$ lint [flags] <project directories>
</pre>

<p class="note"><strong>Note:</strong> The {@code lint} <strong>--show</strong> and <strong>--list</strong>
flags can be used to display the available issues and explanations. </p>


<p>For more information, see
<a href="{@docRoot}tools/debugging/improving-w-lint.html">Improving Your Code with {@code lint}</a>
and <a href="{@docRoot}tools/help/lint.html">lint tool</a>.</p>



<h3 id="annotations">Annotations in Android Studio</h3>
<p>Android Studio supports annotations for variables, parameters, and return values to help you
catch bugs, such as null pointer exceptions and resource type conflicts. The
<a href="{@docRoot}tools/help/sdk-manager.html">Android SDK Manager</a> packages
the {@link android.support.annotation Support-Annotations} library
in the Android Support Repository for use with Android
Studio. Android Studio validates the configured annotations during code inspection. </p>

<p>To add annotations to your code in Android Studio, first add a dependency for the
{@link android.support.annotation Support-Annotations} library:</p>
<ol>
 <li>Select <strong>File &gt; Project Structure</strong>.</li>
 <li>In the <em>Project Structure</em> dialog, select the desired module, click the
 <strong>Dependencies</strong> tab. </li>
 <li>Click the <img src="{@docRoot}images/tools/studio-add-icon.png"/> icon to include a
 <strong>Library dependency</strong>.</li>
 <li>In the <em>Choose Library Dependency</em> dialog, select <code>support-annotations</code> and
 click <strong>Ok</strong>. </li>
</ol> 

<p>The <code>build.gradle</code> file is updated with the <code>support-annotations</code>
dependency.</p>

<p>You can also manually add this dependency to your <code>build.gradle</code> file, as shown in
the following example.  </p>

<pre>
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    <strong>compile 'com.android.support:support-annotations:22.0.0'</strong>
}
</pre>



<h4>Inferring nullability</h4>
<p>A nullability analysis scans the contracts throughout the method hierarchies in your code to
detect:</p>
<ul>
 <li>Calling methods that can return null </li>
 <li>Methods that should not return null </li>
 <li>Variables, such as fields, local variables, and parameters, that can be null </li>
 <li>Variables, such as fields, local variables, and parameters, that cannot hold a null value </li>
</ul>

<p>The analysis then automatically inserts the appropriate null annotations in the detected
locations. </p>

<p>To run a nullability analysis in Android Studio,
select the <strong>Analyze &gt; Infer Nullity</strong>
menu option. Android Studio inserts the Android
{@link android.support.annotation.Nullable @Nullable} and
{@link android.support.annotation.NonNull @NonNull} annotations in detected locations
in your code. After running a null analysis, it's good practice to verify the injected
annotations.</p>

<p class="note"><strong>Note:</strong> The nullability analysis may insert the IntelliJ
<a class="external-link" href="https://www.jetbrains.com/idea/help/-nullable-and-notnull-annotations.html?search=annotations">
<code>&#64;Nullable</code></a> and
<a class="external-link" href="https://www.jetbrains.com/idea/help/-nullable-and-notnull-annotations.html?search=annotations">
<code>&#64;NotNull</code></a> annotations instead of the Android null annotations. When running
a null analysis, manually search and replace any IntelliJ annotations or include
<code>com.intellij:annotations:12.0</code> as a compile dependency in your
<code>build.gradle</code> file. This example includes the IntelliJ annotations 12.0 library as a
dependency in the <code>build.gradle</code> file:

<pre>
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.0.0'
    compile 'com.android.support:support-annotations:22.0.0'
    <strong>compile 'com.intellij:annotations:12.0'</strong>
}
</pre>

</p>


<h4>Validating annotations</h4>
<p>You can also manually add nullability, resource, and enumerated annotations throughout your code
to perform validations for a variety of reference values, such as
<a href="{@docRoot}reference/android/R.string.html"><code>R.string</code></a> resources,
<a href="{@docRoot}guide/topics/resources/drawable-resource.htm"><code>Drawable</code></a>
resources,
<a href="{@docRoot}reference/android/graphics/Color.html"><code>Color</code></a> resources,
and enumerated constants. </p>

<p>Run <strong>Analyze &gt; Inspect Code</strong> to validate the configured annotations. </p>

<p>For a complete list of the supported annotations, either use the auto-complete feature to display
the available options for the <code>import android.support.annotation.</code> statement or
view the contents of the
{@link android.support.annotation Support-Annotations}
library. </p>

<p>For more details about Android annotations, see
<a href="{@docRoot}tools/debugging/annotations.html">Improving Code Inspection with Annotations</a>.



<h3>Dynamic layout preview</h3>
<p>Android Studio allows you to work with layouts in both a <em>Design View</em> </p>
<p><img src="{@docRoot}images/tools/studio-helloworld-design.png" alt="" />
</p>
    <p class="img-caption"><strong>Figure 6.</strong> Hello World App with Design View.</p>

<p>and a <em>Text View</em>. </p>

    <p><img src="{@docRoot}images/tools/studio-helloworld-text.png" alt="" />
    <pclass="img-caption"><strong>Figure 7.</strong> Hello World App with text view.</p>

<p>Easily select and preview layout changes for different device images, display
densities, UI modes, locales, and Android versions (multi-API version rendering).
    <p><img src="{@docRoot}images/tools/studio-api-version-rendering.png" /></p>
    <p class="img-caption"><strong>Figure 8.</strong> Multi-API version rendering.</p>


<p>From the Design View, you can drag and drop elements from the Palette to the Preview or
Component Tree. The Text View allows you to directly edit the XML settings, while previewing
the device display. </p>


<h3>Log messages</h3>
<p>When you build and run your app with Android Studio, you can view adb and device log messages
(logcat) by clicking <strong>Android</strong> at the bottom of the window.</p>

<p>If you want to debug your app with the
<a href="{@docRoot}tools/help/monitor.html">Android Debug Monitor</a>, you can launch it by
clicking <strong>Monitor</strong>
<img src="{@docRoot}images/tools/monitor-studio.png" style="vertical-align:bottom;margin:0;height:19px"/>
in the toolbar. The Debug Monitor is where you can find the complete set of
<a href="{@docRoot}tools/debugging/ddms.html">DDMS</a> tools for profiling your app,
controlling device behaviors, and more. It also includes the Hierarchy Viewer tools to help
<a href="{@docRoot}tools/debugging/debugging-ui.html"> optimize your layouts</a>.</p>