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The OnClick method is called when the button is actually clicked (or tapped). Any code in the OnClick method will run each time we tap the button!
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We just left off with a lot of code
that was generated by auto complete.
0:00
We use on click listeners
like this a lot in Android.
0:05
So it'll make more and
more sense the more you use it.
0:08
This on click method,
0:11
will run when ever this listener
detects a click on our button.
0:14
Just like opening our app
triggers the onCreate method,
0:18
typing on our button will
trigger this onClick method.
0:21
So anytime we click on our button,
0:24
the code that we write inside
these curly brackets will run.
0:26
Let's add a comment in the onClick
method to describe what we'd like to do.
0:31
The button was clicked,
0:34
so update the fact
TextView with a new fact.
0:38
All right, now we need a new fact.
0:44
On the line below our comment, let's
create a new string variable named fact.
0:47
And let's set it equal to in
quotation marks Ostriches
0:52
can run faster than horses.
0:57
And don't forget the semicolon.
1:01
Now we need to update our text
view to show this new fact.
1:03
Remember when we were editing the layout?
1:07
We can change the text of a text view
by editing it's text property or
1:09
by changing it directly
in the layout's XML file.
1:13
Android also allows us to make
these kinds of changes in code.
1:17
On a new line type factTextView.setText
and then hit Enter to autocomplete.
1:21
Notice that there's a list of
different parameters down here.
1:30
This is because there are different
versions of this set text method.
1:33
Each taken different parameters.
1:38
We want this first one because it
only has one parameter for the text.
1:40
Now the data type here, CharSequence,
1:44
might be a little confusing
since we're using a String.
1:47
But a String is just
a sequence of characters, so
1:51
it shouldn't be too surprising that
all Strings are also CharSequences.
1:54
Kind of like how text views are also
views or how dogs are also animals.
2:00
In Android,
2:06
whenever you see a Charsequence,
you can just pass in a string.
2:07
All right, let's type fact in between the
parenthesis to pass in our fact variable
2:11
and now we are ready for
the moment of truth.
2:16
Let's click on the Run button,
or hit Ctrl + Alt on Mac,
2:18
or Shift + F10 on Windows to run our app.
2:22
Looks good.
2:27
Let's click on the button to test it.
2:29
Did you know that ostriches
can run faster than horses?
2:32
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