docs: lint inspection updates

    </div>

  </div>

  <p>

Sometimes your application's layout can slow down your application.

<p>Sometimes your application's layout can slow down your application.

To help debug issues in your layout, the Android SDK provides the Hierarchy Viewer and

  <code>lint</code> tools.

  </p>

<code><a href="{@docRoot}tools/help/lint.html">lint</a></code> tools. </p>

  <p>The Hierarchy Viewer application allows you to debug and optimize your user interface. It

  provides a visual representation of the layout's View hierarchy (the View Hierarchy window)

  and a magnified view of the display (the Pixel Perfect window) to closely examine the pixels

  in your layout.</p>

  <p>Android <code>lint</code> is a static code scanning tool that helps you optimize the layouts and layout

  hierarchies of your applications, as well as detect other common coding problems. You can run it against your layout files or resource

  <p>Android <code><a href="{@docRoot}tools/help/lint.html">lint</a></code> is a static code

  scanning tool that helps you optimize the layouts and layout

  hierarchies of your applications, as well as detect other common coding problems. You can run it

  against your layout files or resource

  directories to quickly check for inefficiencies or other types of problems that could be

  affecting the performance of your application.</p>

        alt=""

        height="600"/>

<p class="img-caption"><strong>Figure 4.</strong> The Pixel Perfect window</p>

<h2 id="lint">Using lint to Optimize Your UI</h2>

<p>The Android {@code lint} tool lets you analyze the XML files that define your application's UI to find inefficiencies in the view hierarchy.</p>

<p class="note"><strong>Note: </strong>The Android <code>layoutopt</code> tool has been replaced by the {@code lint} tool beginning in ADT and SDK Tools revision 16. The {@code lint} tool reports UI layout performance issues in a similar way as <code>layoutopt</code>, and detects additional problems.</p>

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

<p>The Android <a href="{@docRoot}tools/help/lint.html">lint</a> tool lets you analyze the XML

files that define your application's UI to find inefficiencies in the view hierarchy.</p>

<p class="note"><strong>Note: </strong>The Android <code>layoutopt</code> tool has been replaced by the {@code lint} tool beginning in SDK Tools revision 16. The {@code lint} tool reports UI layout performance issues in a similar way as <code>layoutopt</code>, and detects additional problems.</p>

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

      <ol>

        <li><a href="#overview">Overview</a></li>

        <li><a href=#eclipse">Running lint from Eclipse</a></li>

        <li><a href=#studio">Running lint from Android Studio</a></li>

        <li><a href=#commandline">Running lint from the command-line</a></li>

         <li><a href=#config">Configuring lint</a>

            <ol>

		<LI><a href="#eclipse_config">Configuring lint in Eclipse</a></LI>

		<LI><a href="#studio_config">Configuring lint in Android Studio</a></LI>

                <LI><a href="#pref">Configuring the lint file</a></LI>

                <LI><a href="#src">Configuring lint checking in Java and XML source files</a></LI>

            </ol>

In addition to testing that your Android application meets its functional requirements, it's important to ensure that your code has no structural problems. Poorly structured code can impact the reliability and efficiency of your Android apps and make your code harder to maintain. For example, if your XML resource files contain unused namespaces, this takes up space and incurs unnecessary processing. Other structural issues, such as use of deprecated elements or API calls that are not supported by the target API versions, might lead to code failing to run correctly.</p>

<h2 id="overview">Overview</h2>

<p>The Android SDK provides a code scanning tool called {@code lint} that can help you to easily identify and correct problems with the structural quality of your code, without having to execute the app or write any test cases. Each problem detected by the tool is reported with a description message and a severity level, so that you can quickly prioritize the critical improvements that need to be made.  You can also configure a problem's severity level to ignore issues that are not relevant for your project, or raise the severity level. The tool has a command-line interface, so you can easily integrate it into your automated testing process.</p>

<p>The {@code lint} tool checks your Android project source files for potential bugs and optimization improvements for correctness, security, performance, usability, accessibility, and internationalization. You can run {@code lint} from the command-line or from the Eclipse environment.</p>

<p>The Android SDK provides a code scanning tool called <a href="{@docRoot}tools/help/lint.html"><code>lint</code></a>

that can help you to easily identify and correct problems with the structural quality of your code, without having to execute the app or write any test cases. Each problem detected by the tool is reported with a description message and a severity level, so that you can quickly prioritize the critical improvements that need to be made.  You can also configure a problem's severity level to ignore issues that are not relevant for your project, or raise the severity level. The tool has a command-line interface, so you can easily integrate it into your automated testing process.</p>

<p>The {@code lint} tool checks your Android project source files for potential bugs and optimization improvements for correctness, security, performance, usability, accessibility, and internationalization. You can run {@code lint} from the command-line or from Android Studio.</p>

<p class="note"><strong>Note:</strong> In Android Studio, additional

<a href="https://www.jetbrains.com/idea/help/inspection-basics.html?search=inspection" class="external-link"

target="_blank">IntelliJ code inspections</a> run when your code is compiled in Android Studio to

streamline code review.</p>

<p>Figure 1 shows how the {@code lint} tool processes the application source files.</p>

<img id="Fig1" src="{@docRoot}images/tools/lint.png" alt="">

<p class="img-caption"><strong>Figure 1.</strong> Code scanning workflow with the {@code lint} tool</p>

<dt><b>The <code>lint.xml</code> file</b></dt>

<dd>A configuration file that you can use to specify any {@code lint} checks that you want to exclude and to customize problem severity levels.</dd>

<dt><b>The {@code lint} tool</b></dt>

<dd>A static code scanning tool that you can run on your Android project from the command-line or from Eclipse.   The {@code lint} tool checks for structural code problems that could affect the quality and performance of your Android application. It is strongly recommended that you correct any errors that {@code lint} detects before publishing your application.</dd>

<dd>A static code scanning tool that you can run on your Android project from the command-line or Android Studio.  The {@code lint} tool checks for structural code problems that could affect the quality and performance of your Android application. It is strongly recommended that you correct any errors that {@code lint} detects before publishing your application.</dd>

<dt><b>Results of {@code lint} checking</b></dt>

<dd>You can view the results from {@code lint} in the console or in the <strong>Lint Warnings</strong> view in Eclipse.  Each issue is identified by the location in the source files where it occurred and a description of the issue.</dd>

<dd>You can view the results from {@code lint} in the console or in the <strong>Event Log</strong> in Android Studio.  Each issue is identified by the location in the source files where it occurred and a description of the issue.</dd>

</dl>

<p>The {@code lint} tool is automatically installed as part of the Android SDK Tools revision 16 or higher. If you want to use {@code lint} in the Eclipse environment, you must also install the Android Development Tools (ADT) Plugin for Eclipse revision 16 or higher. For more information about installing the SDK or the ADT Plugin for Eclipse, see <a href="http://developer.android.com/sdk/installing.html">Installing the SDK.</a></p>

<p>The {@code lint} tool is automatically installed as part of the Android SDK Tools revision 16 or higher.</p>

<h2 id="studio">Running lint in Android Studio</h2>

<p>In Android Studio, the configured <code>lint</code> and

IDE inspections run automatically whenever you build your app. The IDE inspections are

configured along with the {@code lint} checks to run

<a href="https://www.jetbrains.com/idea/help/inspection-basics.html?search=inspection" class="external-link"

target="_blank">IntelliJ code inspections</a> to streamline code review.</p>

<p class="note"><strong>Note:</strong> To view and modify inspection severity

levels, use the <strong>File &gt; Settings &gt; Project Settings</strong> menu to open the

<em>Inspection Configuration</em> page with a list of the supported inspections.</p>

<p>With Android Studio, you can also run {@code lint} inspections for a specific build variant,

or for all build variants from the <code>build.gradle</code> file. Add the

<code>lintOptions</code> property to the <code>android</code> settings in the build file.

This code snippet from a Gradle build file shows how to set the <code>quiet</code> option to

<code>true</code> and the <code>abortOnError</code> option to <code>false</code>. </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>To manually run inspections in Android Studio, from the application or right-click menu,

choose <strong>Analyze &gt; Inspect Code</strong>. The <em>Specify Inspections Scope</em> dialog

appears so you can specify the desired inspection scope and profile.</p>

<h2 id="eclipse">Running lint from Eclipse</h2>

<p>If the ADT Plugin is installed in your Eclipse environment, the {@code lint} tool runs automatically when you perform one of these actions:</p>

<ul>

<LI>Export an APK</LI>

<LI>Edit and save an XML source file in your Android project (such as a manifest or layout file)</LI>

<LI>Use the layout editor in Eclipse to make changes</LI>

</ul>

<p>Note that when you export an APK, {@code lint} only runs an automatic check for fatal errors and aborts the export if fatal errors are found. You can turn off this automatic checking from the <strong>Lint Error Checking</strong> page in Eclipse Preferences. </p>

<p>The output is displayed in the <strong>Lint Warnings</strong> view. If the <strong>Lint Warnings</strong> view is not showing in the workbench, you can bring it up from the Eclipse menu by clicking <strong>Window &gt; Show View &gt; Other &gt;  Android &gt; Lint Warnings</strong>.</p>

<p>Figure 2 shows an example of the output in the Lint Warnings view.</p>

<img id="Fig2" src="{@docRoot}images/tools/lint_output.png" alt="">

<p class="img-caption"><strong>Figure 2.</strong> Sample output in the <strong>Lint Warnings</strong> view</p>

<p>You can also run a {@code lint} scan manually on your Android project in Eclipse by right-clicking on the project folder in the Package Explorer > <strong>Android Tools  &gt; Run Lint: Check for Common Errors</strong>.</p>

<h2 id="commandline">Running lint from the Command-Line</h2>

<p>By default, when you run a {@code lint} scan, the tool checks for all issues that are supported by {@code lint}.  You can also restrict the issues for {@code lint} to check and assign the severity level for those issues. For example, you can disable {@code lint} checking for specific issues that are not relevant to your project and configure {@code lint} to report non-critical issues at a lower severity level.</p>

<p>You can configure {@code lint} checking at different levels:</p>

<ul>

<LI>Globally, for all projects</LI>

<li>Per project</li>

<li>Per file</li>

<li>Per Java class or method (by using the <code>&#64;SuppressLint</code> annotation), or per XML element (by using the <code>tools:ignore</code> attribute.</li>

<LI>Globally, for the entire project</LI>

<li>Per project module</li>

<li>Per production module</li>

<li>Per test module</li>

<li>Per open files</li>

<li>Per class hierarchy</li>

<li>Per Version Control System (VCS) scopes</li>

</ul>

<h3 id="eclipse_config">Configuring lint in Eclipse</h3>

<p>You can configure global, project-specific, and file-specific settings for {@code lint} from the Eclipse user interface.</p>

<h3 id="studio_config">Configuring lint in Android Studio</h3>

<p>Android Studio allows you to enable or disable individual inspections and configure

project-global, directory-specific, and file-specific settings for {@code lint}.</p>

<p>You can manage inspection profiles and configure inspection severity within Android Studio using

the <strong>File &gt; Settings &gt; Project Settings</strong> menu to open the <em>Inspections</em>

page with a list of the supported profiles and inspections.</p>

<p><img src="{@docRoot}images/tools/studio-inspections-config.png" alt="" /> </p>

<p class="img-caption"><strong>Figure 3.</strong> Inspection Configuration</p> 

<h4>Global preferences</h4>

<ol>

<LI>Open <strong>Window  &gt; Preferences  &gt; Android  &gt; Lint Error Checking</strong>.</LI>

<li>Specify your preferences and click <b>OK</b>.</li>

<li>To specify global project settings, select the project folder in the Project View and choose

<strong>Analyze &gt; Inspect Code</strong>.</li>

<li>Specify your inspection scope and profile, and click <b>OK</b>.</li>

</ol>

<p>These settings are applied by default when you run {@code lint} on your Android projects in Eclipse.</p>

<p>The configured settings run the specified {@code lint} inspections. The {@code lint}

inspections are also run whenever you build and run your Android project and modules.</p>

<h4>Project and file-specific preferences</h4>

<h4>Module and file-specific preferences</h4>

<ol>

<LI>Run the {@code lint} tool on your project by right-clicking on your project folder in the Package Explorer and selecting  <strong>Android Tools &gt; Run Lint: Check for Common Errors</strong>. This action brings up the <strong>Lint Warnings</strong> view which displays a list of issues that {@code lint} detected in your project.</LI>

<li>From the <strong>Lint Warnings</strong> view, use the toolbar options to configure {@code lint} preferences for individual projects and files in Eclipse. The options you can select include:

<ul>

<LI><b>Suppress this error with an annotation/attribute</b> - If the issue appears in a Java class, the {@code lint} tool adds a <code>&#64;SuppressLint</code> annotation to the method where the issue was detected.  If the issue appears in an {@code .xml} file, {@code lint} inserts a <code>tools:ignore</code> attribute to disable checking for the {@code lint} issue in this file.</LI>

<LI><b>Ignore in this file</b> - Disables checking for this {@code lint} issue in this file.</LI>

<li><b>Ignore in this project</b>  - Disables checking for this {@code lint} issue in this project.</li>

<li><b>Always ignore</b> - Disables checking for this {@code lint} issue globally for all projects.</li>

</ul>

</li>

<LI>Run the {@code lint} tool on your module by right-clicking on your module folder or file in the Project View and selecting  <strong>Analyze &gt; Inspect Code</strong>. This displays the {@code lint} inspection results

with a list of issues that {@code lint} detected in your module.</LI>

<li>From the <strong>Lint Warnings</strong> view, use the toolbar options to configure {@code lint} preferences for individual modules and files, and set the issue display options.</li>

</ol>

<p>If you select the second or third option, the {@code lint} tool automatically generates a <code>lint.xml</code> file with these configuration settings in your Android application project folder.  </p>

<h3 id="pref">Configuring the lint file</h3>

<p>You can specify your {@code lint} checking preferences in the <code>lint.xml</code> file.  If you are creating this file manually, place it in the root directory of your Android project.  If you are configuring {@code lint} preferences in Eclipse, the <code>lint.xml</code> file is automatically created and added to your Android project for you.</p>

<p>You can specify your {@code lint} checking preferences in the <code>lint.xml</code> file.  If you are creating this file manually, place it in the root directory of your Android project.  If you are configuring {@code lint} preferences in Android Studio, the <code>lint.xml</code> file is automatically created and added to your Android project for you.</p>

<p>The <code>lint.xml</code> file consists of an enclosing <code>&lt;lint&gt;</code> parent tag that contains one or more children <code>&lt;issue&gt;</code> elements.  Each <code>&lt;issue&gt;</code> is identified by a unique <code>id</code> attribute value, which is defined by {@code lint}.</p>

<pre>

<?xml version="1.0" encoding="UTF-8"?>

<h3 id="src">Configuring lint checking in Java and XML source files</h3>

<p>You can disable {@code lint} checking from your Java and XML source files.</p>

<p class="note"><strong>Tip: </strong>If you are using Eclipse, you can use the <strong>Quick Fix</strong> feature to automatically add the annotation or attribute to disable {@code lint} checking to your Java or XML source files:

<ol>

<LI>Open the Java or XML file that has a {@code lint} warning or error in an Eclipse editor.</LI>

<LI>Move your cursor to the location in the file where is {@code lint} issue is found, then press <code>Ctrl+1</code> to bring up the <strong>Quick Fix</strong> pop-up.</LI>

<li>From the <strong>Quick Fix</strong> pop-up, select the action to add an annotation or attribute to ignore the {@code lint} issue.</li>

</ol>

<p class="note"><strong>Tip: </strong>If you are using Android Studio, you can use the

<strong>File &gt; Settings &gt; Project Settings &gt; Inspections</strong> feature to manage the

{@code lint} checking to your Java or XML source files.

</p>

<h4>Configuring lint checking in Java</h4>

</div>

<p>The Android {@code lint} tool is a static code analysis tool that checks your Android project source files for potential bugs and optimization improvements for correctness, security, performance, usability, accessibility, and internationalization.</p>

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

<h2 id="syntax">Syntax</h2>

<p>In Android Studio, the configured <code>lint</code> and other IDE inspections run automatically

whenever you compile your program. You can also manually run inspections in Android Studio

by selecting <strong>Analyze &gt; Inspect Code</strong> from the application or right-click menu.

The <em>Specify Inspections Scope</em> dialog appears so you can specify the desired inspection 

profile and scope.</p>

<p>For more information on enabling {@code lint} inspections and running {@code lint},

see <a href="{@docRoot}tools/debugging/improving-w-lint.html">Improving Your Code with lint</a>.</p>

<h2 id="syntax">Command Line Syntax</h2>

<p>

<pre>lint [flags] &lt;project directory&gt;</pre>

For example, you can issue the following command to scan the Java and XML files under the {@code myproject}  directory and its subdirectories. The result is displayed on the console.

For example, you can issue the following command to scan the Java and XML files under the

{@code myproject}  directory and its subdirectories. The result is displayed on the console.

<pre>lint myproject</pre>

You can also use {@code lint} to check for a specific issue. For example, you can run the following command to scan the files under the {@code myproject} directory and its subdirectories to check for XML attributes missing the Android namespace prefix. The issue ID {@code MissingPrefix} tells lint to only scan for this issue.

<h2 id="config_keywords">Configuring Java and XML Source Files</h2>

<p>To configure lint checking, you can apply the following annotation or attribute to the source files in your Android project. </p>

<ul>

<LI>To disable lint checking for a specific Java class or method, use the <code>@SuppressLint</code> annotation. </LI>

<li>To disable lint checking for specific sections of your XML file, use the <code>tools:ignore</code> attribute. </li>

<LI>To disable {@code lint} checking for a specific Java class or method, use the <code>@SuppressLint</code>

annotation. </LI>

<li>To disable {@code lint} checking for specific sections of your XML file, use the

<code>tools:ignore</code> attribute. </li>

</ul>

<p>You can also specify your lint checking preferences for a specific Android project in the lint.xml file.  For more information on configuring lint, see <a href="{@docRoot}tools/debugging/improving-w-lint.html">Improving Your Code with lint</a>.</p>

<p>You can also specify your {@code lint} checking preferences for a specific Android project in

the <code>lint.xml</code> file.  For more information on configuring {@code lint}, see

<a href="{@docRoot}tools/debugging/improving-w-lint.html">Improving Your Code with lint</a>.</p>