| page.title=Managing the Activity Lifecycle |
| page.tags=activity lifecycle |
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| <h2>Dependencies and prerequisites</h2> |
| <ul> |
| <li>How to create an Android project (see <a |
| href="{@docRoot}training/basics/firstapp/creating-project.html">Creating an Android |
| Project</a>)</li> |
| </ul> |
| |
| |
| <h2>You should also read</h2> |
| <ul> |
| <li><a href="{@docRoot}guide/components/activities.html">Activities</a></li> |
| </ul> |
| |
| |
| <h2>Try it out</h2> |
| |
| <div class="download-box"> |
| <a href="http://developer.android.com/shareables/training/ActivityLifecycle.zip" |
| class="button">Download the demo</a> |
| <p class="filename">ActivityLifecycle.zip</p> |
| </div> |
| |
| </div> |
| </div> |
| |
| <p>As a user navigates through, out of, and back to your app, the |
| {@link android.app.Activity} instances in your app transition between different states in their |
| lifecycle. For instance, when your |
| activity starts for the first time, it comes to the foreground of the system and receives user |
| focus. During this process, the Android system calls a series of lifecycle methods on the |
| activity in which you set up the user interface and other components. If the user performs an |
| action that starts another activity or switches to another app, the system calls another set of |
| lifecycle methods on your activity as it moves into the background (where the activity is no |
| longer visible, but the instance and its state remains intact).</p> |
| |
| <p>Within the lifecycle callback methods, you can declare how your activity behaves when the |
| user leaves and re-enters the activity. For example, if you're building a streaming video player, |
| you might pause the video and terminate the network connection when the user switches to another |
| app. When the user returns, you can reconnect to the network and allow the user to resume the video |
| from the same spot.</p> |
| |
| <p>This class explains important lifecycle callback methods that each {@link |
| android.app.Activity} instance receives and how you can use them so your activity does what the |
| user expects and does not consume system resources when your activity doesn't need them.</p> |
| |
| <h2>Lessons</h2> |
| |
| <dl> |
| <dt><b><a href="starting.html">Starting an Activity</a></b></dt> |
| <dd>Learn the basics about the activity lifecycle, how the user can launch your app, and how |
| to perform basic activity creation.</dd> |
| <dt><b><a href="pausing.html">Pausing and Resuming an Activity</a></b></dt> |
| <dd>Learn what happens when your activity is paused (partially obscured) and resumed and what you |
| should do during these state changes.</dd> |
| <dt><b><a href="stopping.html">Stopping and Restarting an Activity</a></b></dt> |
| <dd>Learn what happens when the user completely leaves your activity and returns to it.</dd> |
| <dt><b><a href="recreating.html">Recreating an Activity</a></b></dt> |
| <dd>Learn what happens when your activity is destroyed and how you can rebuild the activity |
| state when necessary.</dd> |
| </dl> |
| |