- What are Fragments? 2:15
- My First Fragment 6:05
- Fragments? 5 questions
- Adding Fragments to Activities 4:13
- Adding a Fragment 2 objectives
- Making a List 8:56
- Checking It Twice 3:42
- Handling Clicks 5:20
- Handling Clicks 2 objectives
- Fragment Lifecycle 7:00
- Fragment Lifecycle 5 questions
- Keeping Track of Instance State 6:09
- Saving State 2 objectives
Preview
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My First Fragment
6:05In this video we'll get our feet wet by creating a Fragment!
First things first.
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We need to create the project.
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Let's create a new project and
name it Smells Like Bakin.
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And let's leave everything else default.
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Make sure this is set to empty
activity and then hit Finish.
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Before we get started,
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there are a few starter files that
you should add to your project.
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Start by downloading
the images we'll be using
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from the link below in
the teacher's notes.
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Once you've got the images, copy and
paste them into the drawable folder.
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Next create a new class called Recipes.
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And copy and paste the code for
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this class from the teacher's
notes into your new Recipe class.
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We'll be using this class to store
information about our recipes.
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Notice that we've got a few
public static arrays.
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We've got one for the recipe names.
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One for the resource IDs.
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Another for the ingredients.
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And one last array for the directions.
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The Recipes class has all
the information we need to make our app.
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Now, let's move on to creating
our very first fragment.
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And that fragment is the list
fragment from the phone layout.
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Let's start by creating a new
layout file for this fragment.
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And let's call it fragment_list.
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Fragments need to get their
layouts from somewhere.
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And just like activities,
an easy way to specify the layout for
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a fragment is through an XML file.
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Because we're still trying
to figure out fragments,
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let's just quickly add
a text view to the middle.
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Change its text to say yay fragments.
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And leave it at that for now.
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Then, let's create a new
class named ListFragment.
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This class will represent the list
we saw earlier on the phone.
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And it will display our
new fragment list layout.
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And since this is a fragment, we should
make it extend to fragment class.
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And notice that there are actually
two fragment classes.
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One from the android.app package, and one
from the android.support.v4.app package.
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If we need to support less than API 11 we
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need to pick the fragment
from the support package.
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But since our min SDK version is 15, which
was defaulted then we created the project,
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we'll be fine picking
the regular fragment class.
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Next up let's override our
fragments on Create view method.
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Ctrl+O onCreateView > Enter.
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The view returned by this method is
what will be displayed by our fragment.
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So we need to return a view that
represents our fragment list layout.
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We can do this by using
the LayoutInflator parameter.
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Remember allowed LayoutInflater is what
we use to turn XML layouts into views.
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Let's get rid of this
line with the return and
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create a new variable for
the view we'd like to return.
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View, view.
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And let's set it equal
to inflater.inflate.
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And for the first argument, it looks
like we need to provide a resource ID.
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So let's pass an R.layout fragment list.
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Then, for the second argument,
we need a view group.
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This view group will be where
our new view gets added.
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And luckily, it's provided for
us as the container parameter.
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So I'll just copy that and
then pass that and as the second argument.
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Looking good.
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Last but not least,
let's return our view variable.
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Now that we've got our fragment,
let's head over to main activity and
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make the magic happen.
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But first let's take a quick detour
to our activities layout file,
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and delete the text view.
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When we add a fragment to an activity,
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we have to specify where in the activity
we should add the fragment.
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One way to do this,
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is to put the fragment directly into
the XML of the activities layout.
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To do this we just use the fragment tag.
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And then specify which fragment to
show by using the name attribute.
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The other way to add a fragment
to an activity is to use a view
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group as a placeholder and add or remove
fragments from that view group and code.
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It's just an empty view group with the
sole purpose of reserving a spot in our
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activities UI for our fragments.
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Since we'll be using a few different
fragments as the main display,
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let's go with the view group approach.
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And I'll delete this fragment tag.
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A good view group choice
would be a frame layout.
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Since we'll only be showing one fragment
at a time, the list or the details.
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Let's change RelativeLayout
to FrameLayout.
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Then let's give this an ID of placeholder
so we can reference it from our activity.
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Android id placeHolder.
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Lastly, let's get rid of
the four padding attributes.
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If we want padding,
we'll do it in the fragments.
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In the next video, we'll make
the jump over to main activity and
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see our new fragment in action.
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