android_frameworks_base/docs/html/training/appbar/setting-up.jd

page.title=Setting Up the App Bar
page.tags="appbar","actionbar", "toolbar"
helpoutsWidget=true
trainingnavtop=true

@jd:body

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

    <h2>This lesson teaches you to</h2>

    <ol>
      <li><a href="#add-toolbar">Add a Toolbar to an Activity</a></li>
      <li><a href="#utility">Use App Bar Utility Methods</a></li>
    </ol>

    <h2>You should also read</h2>
    <ul>
      <li><a href="{@docRoot}tools/support-library/setup.html"
    >Setting Up the Support Library</a></li>
    </ul>
  </div>
</div>


<p>
  In its most basic form, the action bar displays the title for the activity on
  one side and an <em>overflow menu</em> on the other. Even in this simple
  form, the app bar provides useful information to the users, and helps to give
  Android apps a consistent look and feel.
</p>

<img src="{@docRoot}images/training/appbar/appbar_basic_2x.png"
    srcset="{@docRoot}images/training/appbar/appbar_basic.png 1x,
        {@docRoot}images/training/appbar/appbar_basic_2x.png 2x"
    width="400" alt="" />
<p class="img-caption"><strong>Figure 1.</strong> An app bar with the app
title and overflow menu.</a>

<p>
  Beginning with Android 3.0 (API level 11), all
  activities that use the default theme have an {@link android.app.ActionBar}
  as an app bar. However, app bar features have gradually been added to the
  native {@link android.app.ActionBar} over various Android releases. As a
  result, the native {@link android.app.ActionBar} behaves differently
  depending on what version of the Android system a device may be using. By
  contrast, the most recent features are added to the support library's version
  of {@link android.support.v7.widget.Toolbar}, and they are available on any
  device that can use the support library.
</p>

<p>
  For this reason, you should use the support library's {@link
  android.support.v7.widget.Toolbar} class to implement your activities' app
  bars. Using the support library's toolbar helps ensure that your app will
  have consistent behavior across the widest range of devices. For example, the
  {@link android.support.v7.widget.Toolbar} widget provides a <a href=
  "{@docRoot}design/material/index.html">material design</a> experience on
  devices running Android 2.1 (API level 7) or later, but the native action
  bar doesn't support material design unless the device is running Android 5.0
  (API level 21) or later.
</p>

<h2 id="add-toolbar">Add a Toolbar to an Activity</h2>

These steps describe how to set up a {@link android.support.v7.widget.Toolbar}
as your activity's app bar:

<ol>
  <li>Add the
  <a href="{@docRoot}tools/support-library/features.html#v7-appcompat">v7
  appcompat</a> support library to your project, as described in <a href=
  "{@docRoot}tools/support-library/setup.html">Support Library Setup</a>.
  </li>

  <li>Make sure the activity extends {@link
  android.support.v7.app.AppCompatActivity}:

    <pre>
public class MyActivity extends AppCompatActivity {
  // ...
}
</pre>
    <p class="note">
      <strong>Note:</strong> Make this change for every activity in your app
      that uses a {@link android.support.v7.widget.Toolbar} as an app bar.
    </p>
  </li>

  <li>In the app manifest, set the <a href=
  "{@docRoot}guide/topics/manifest/application-element.html"><code>&lt;application&gt;</code></a>
  element to use one of appcompat's {@link
  android.support.v7.appcompat.R.style#Theme_AppCompat_NoActionBar NoActionBar}
  themes. Using one of these themes prevents the app from using the native
  {@link android.app.ActionBar} class to provide the app bar. For example:

    <pre>
&lt;application
    android:theme="&#64;style/Theme.AppCompat.Light.NoActionBar"
    /&gt;
</pre>
  </li>

  <li>Add a {@link android.support.v7.widget.Toolbar} to the activity's layout.
  For example, the following layout code adds a {@link
  android.support.v7.widget.Toolbar} and gives it the appearance of floating
  above the activity:

    <pre>
&lt;android.support.v7.widget.Toolbar
   android:id="&#64;+id/my_toolbar"
   android:layout_width="match_parent"
   android:layout_height="?attr/actionBarSize"
   android:background="?attr/colorPrimary"
   android:elevation="4dp"
   android:theme="&#64;style/ThemeOverlay.AppCompat.ActionBar"
   app:popupTheme="&#64;style/ThemeOverlay.AppCompat.Light"/&gt;
</pre>
    <p>
      The <a href=
      "https://www.google.com/design/spec/what-is-material/elevation-shadows.html#elevation-shadows-shadows">
      Material Design specification</a> recommends that app bars have an
      elevation of 4 dp.
    </p>

    <p>
      Position the toolbar at the top of the activity's
      <a href="{@docRoot}guide/topics/ui/declaring-layout.html">layout</a>,
      since you are using it as an app bar.
    </p>
  </li>

  <li>In the activity's {@link android.app.Activity#onCreate onCreate()}
  method, call the activity's {@link
  android.support.v7.app.AppCompatActivity#setSupportActionBar
  setSupportActionBar()} method, and pass the activity's toolbar. This method
  sets the toolbar as the app bar for the activity. For example:

    <pre>
&#64;Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_my);
    <strong>Toolbar myToolbar = (Toolbar) findViewById(R.id.my_toolbar);
    setSupportActionBar(myToolbar);</strong>
    }
</pre>
  </li>
</ol>

<p>
  Your app now has a basic action bar. By default, the action bar contains just
  the name of the app and an overflow menu. The options menu initially contains
  just the <strong>Settings</strong> item. You can add more actions to the
  action bar and the overflow menu, as described in <a href=
  "actions.html">Adding and Handling Actions</a>.
</p>

<h2 id="utility">Use App Bar Utility Methods</h2>

<p>
  Once you set the toolbar as an activity's app bar, you have access to the
  various utility methods provided by the
  <a href="{@docRoot}tools/support-library/features.html#v7-appcompat">v7
  appcompat</a> support library's {@link
  android.support.v7.app.ActionBar} class. This approach lets you do a number of useful
  things, like hide and show the app bar.
</p>

<p>
  To use the {@link android.support.v7.app.ActionBar} utility methods, call the
  activity's {@link
  android.support.v7.app.AppCompatActivity#getSupportActionBar
  getSupportActionBar()} method. This method returns a reference to an
  appcompat {@link android.support.v7.app.ActionBar} object.
  Once you have that reference, you can call any of the {@link
  android.support.v7.app.ActionBar} methods to adjust the app bar. For example,
  to hide the app bar, call {@link android.support.v7.app.ActionBar#hide
  ActionBar.hide()}.
</p>