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The Problem with Activities
2:03The goal of this course is to learn about the Android activity lifecycle. In this video we'll see why the activity lifecycle is such an important topic. Let's get started!
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Hi, I'm Ben.
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In this course, we're going to
learn about the Activity Lifecycle.
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In the Android operating system, almost
all apps start and end with an activity.
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Activities get created,
paused, stopped and eventually,
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destroyed and
it's our responsibility as developers
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to make sure that we handle each of
these lifecycle changes gracefully.
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There's a bunch of different lifecycle
methods but before we get into that,
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let's see why it's so important that
we manage the activity lifecycle.
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Here's the fun facts project
from the very first course.
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Let's see what happens when we get
a new fun fact and then rotate the app.
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Instead of showing the new fact,
it's showing the first fact.
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It turns out, activities are entirely
recreated when the orientation changes.
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At first glance, this probably seems
a little weird but since different
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orientations require different layouts,
and those layouts require
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different resources, activities are always
recreated on an orientation change.
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Since Android handles
recreating the activity,
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all we have to handle is saving and
restoring our activity state.
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For example,
if a user is halfway down a giant list and
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they rotate the app, normally,
the activity will be restarted, and
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they'll be looking at the top of the list.
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But if we hook into
the right lifecycle events,
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we can save off their position in
the list when the activity stops and
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restore that position
when it gets recreated.
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That way, the user will be totally unaware
of what just happened behind the scenes.
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In the rest of this course,
we'll see how we can use a bundle to
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handle these kinds of changes, how we can
save data using shared preferences and
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we'll finish with a project that will you
a chance to show off what you've learned.
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It's a lot to cover.
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Let's get started.
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