- Getting Text from an EditText 8:21
- Getting Text from an EditText 1 objective
- Adding a Second Activity 1:57
- Introducing Intents 2:23
- Starting a New Activity 2 objectives
- Sending Data to a New Activity 2:53
- Putting Data in an Intent 1 objective
- Getting Data from an Intent 3:06
- Getting Data from an Intent 2 objectives
- Investigating a NullPointerException 3:21
- Introducing String Resources 2:41
- Getting Resources from the Context 4:20
- Using String Resources 3 objectives
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Getting Text from an EditText
8:21Getting input from an EditText is as simple as calling a method on it. But we need to make sure we do it in the right place, and that we know what to do with what the method returns.
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[MUSIC]
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[SOUND] We just proved that we can
enter text in the main field, great.
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But how do we access that text and
use it in our code?
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>> Let's go back into our
MainActivity class file.
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Now notice over here I have a new class
called InteractiveStoryApplication.
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If you didn't watch the optional video in
the last section, don't worry about this.
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You do not need this.
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It's only there if you went
through that optional video.
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So here in our class let's
add a new member variable.
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private EditText, and
we'll call this nameField.
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Could call it name EditText but I kind of
get tired typing EditText over and over.
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Field is a bit easier and
means the same thing.
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Remember that private here means that this
field can only be used inside this class,
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which is what we want.
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We will generally make member
variables private like this,
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though sometimes we want them
to be public or protected.
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Making things public is okay, but it does
open up our code to more opportunities for
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misuse or unintended consequences.
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Now why is onCreate protected down here?
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Protected is kind of a cross
between public and private.
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It makes things available to other
classes in the same package or
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subclasses of this class.
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This is useful in certain situations, but
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we'll talk about that when we
come across it in the future.
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You may already know all about
inheritance from Java, but
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we haven't really talked
about it much yet.
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And we're going to deal
with it more in the future.
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Briefly though, inheritance is an object
oriented concept where a class
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can inherit things from a parent
class by extending it as a subclass.
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So we see this with MainActivity.
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We are extending the AppCompatActivity
class, which means that our main activity
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is a subclass, or
child of the AppCompatActivity class.
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That means that MainActivity is
the same as a regular AppCompatActivity
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plus all the extra stuff
that we add to it in here.
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It's worth pointing out that
AppCompatActivity itself extends
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FragmentActivity, which extends Activity.
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Every kind of special activity in
Android is somehow a descendant of this
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base activity class.
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And if we keep walking
up this parent-chain,
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we end up at the mother of all objects,
java.lang.Object.
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There's one more thing back in here.
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We haven't talked about this Override
annotation that we see here.
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Java annotations like this are hints
to the compiler that help us
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while developing.
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They aren't actually required for
the code to work.
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This hint states that this method
is overriding the onCreate method
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of the parent class.
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We see this same thing a lot in Android.
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Anyhow, we can set our new member
variable here in the onCreate method.
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Remember to do it after setContentView,
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because that's the method that
attaches our layout to the activity.
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And without that, we won't have anything
for the edit text to be set to.
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So let's start typing nameField = and
then we'll call findView by ID.
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But remember that we need to
cast it to the appropriate view.
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Because findViewById
returns a generic view.
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And EditText is a subclass
of the View class.
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For the ID we want R.id.
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and we called it nameEditText.
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Now where should we try to access
the value that the user typed
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inside this EditText.
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It won't do us much good to do
anything here in the onCreate method.
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Because this only runs when
the activity is first created and
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the EditText will be blank.
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This method sets up the activity and then
we're ready to accept input from the user,
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that's why we put a button on the screen.
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The user should enter their name
before tapping on the button.
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Remember what code we used
when the button is tapped?
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That's right, an onClickListener.
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So let's add a new member variable
up here, call this private Button,
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startButton, And
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then I'm gonna give myself a little
bit more room on this screen.
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I'm going to collapse
the import statements, and
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add a few lines at the bottom.
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And now we can set button here,
startButton = We'll cast to a button.
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Call find view by id and
type R.button nope and
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Type R.id.startButton.
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On the new line we can set
the onClickListener for it.
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startbutton.setOnClickListener then we
want to type new onClickListener and
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we get a View.onClickListener with
an onClick method that we can override.
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Okay so in here we're going to get
the user's name which is text, so
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let's create a string variable and
we'll name it name.
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Now how can we set it, but we want to
call a method on our EditText variable.
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So let's type name, field, and
type dot and take a look at auto complete.
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Now you might be tempted to call something
like toString which is here at
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the top of mine.
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But that would just convert
the EditText object,
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nameField, to its string representation,
which is not what we need.
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That's not the user's name.
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If you're curious what it looks like,
try it out and log it.
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And take a look at what it prints.
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We want to getText() from the EditText, so
select that method and add a semicolon.
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But wait, we have an error.
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If we hover over it, we see that
it's an incompatible types error.
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It's requiring a string from the left, but
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it found something called
android.text.Editable.
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So, what kind of type is this and
how should we fix it?
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Well, I know from experience, but
how would you figure this out on your own?
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Well, besides watching this video.
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Let's try to google it.
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So let's phrase our problem.
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We're trying to get text from edittext and
there it is from autocomplete,
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and here is a few answers that
look like they might be helpful.
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I'll click on this first one here
which is from stack overflow.
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Okay, so this person is trying to
get the value of an edittext field.
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And if we scroll down,
we can see a working example.
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And this looks a lot like our own code.
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So they've got an EditText here, and
down inside the onClickListener they're
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calling getText, and then they're chaining
the method toString at the end of it.
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Okay so what's happening is that
getText returns a different data type,
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the editable data type.
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And we need to convert an editable
string to a regular string.
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So if we call .toString here,
it does the conversion for us.
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And now we have the name in our variable.
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Let's use a toast here to display it so
that we can test it out.
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I'm old fashioned and I still like to
use toast messages for this purpose.
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But you could certainly use something
else like a snack bar message
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if you're more comfortable with that.
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So on a new line,
let's type Toast.makeText.
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For the context, let's pass in this,
then we'll pass in the name.
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And then we need a length,
which we can use Toast.LENGTH_LONG.
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At the end, we want to chain
the show method to make sure our
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Toast actually shows up.
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And we have an error.
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Let's hover over it to see what it says.
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So it says cannot resolve the method and
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it gives us the parameter with the
different parameters that we passed in.
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Now this is a common error which
is why I wanted to show here.
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The problem is that we're dealing
with this anonymous inner class.
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What that means is inside this
call to setOnClickListener,
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we are creating a brand new mini class.
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It's anonymous, meaning we have
not defined it in its own file or
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given it a name.
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Because of that the scope
of this variable changes.
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It's now referring to this class,
this anonymous class,
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instead of the overall activity class,
which is the context that we need.
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This method now thinks that this is
a view.onClickListener instead of activity
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and that's why we see it in
the error message down here.
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It's an anonymous View at onClickListener.
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So whenever we are in an anonymous
inner class like this,
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we can reference the parent
activity by its full name.
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So instead of just this,
if we type main activity.this,
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we can now get the context
of the parent activity.
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We use these anonymous inner
classes a lot in android.
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They are useful because they let us
create an instance of an object like
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this with certain extra details,
such as overloading the method.
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This is generally more concise and easy to
understand in creating a new subclass or
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new member variable.
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But, it is up to you to use
whichever method you prefer.
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Okay.
So our error is now resolved and
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if we run the app,
it should build without any errors.
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And now whatever we type,
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in the edit text, if we tap on the button,
there we go, cool.
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All right.
So this one example really applies to all
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kinds of data input.
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There might be different controls or
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methods depending on the data, but
knowing how to use an EditText
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means that you can easily figure out how
to use other types of input widgets.
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Dates, for example,
use a different widget on a screen, but
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the basic idea to get
the data is the same.
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Coming up in the next section,
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we'll see how to transfer that data to
a new activity, where we can use it
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in our story, but because practice makes
perfect how about a little practice first?
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