- 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
Preview
Video Player
00:00
00:00
Introducing Intents
2:23Activities (and many other things in Android) are started using an object called an Intent. The intent of this Intent is to start another Activity. :)
So, when you as a person intend to do
a task, it means that you've thought about
0:00
what you wanna do, and
your intent is to do it.
0:04
You just need to start and
maybe you need a little help.
0:07
In Android, it's the same basic idea,
0:10
but it's wrapped up in an intent
object that we can use in code.
0:12
An intent is what we use when we intend
to do something in an Android app.
0:16
We usually use them to start a new task,
and
0:20
that task can be something like
starting a new activity, or
0:22
maybe handing something off to another app
like a video player, or a messaging app.
0:25
Back in our code, let's declare a new
Intent object named, simply, intent.
0:30
We'll set it equal to a new Intent,
with parentheses, and add a semicolon.
0:35
Now, there are a few different
constructors we can use.
0:40
So, if we go back between the parentheses,
we can hit Cmd+P on a Mac, or
0:43
Ctrl+P on Windows, to bring up some help.
0:47
We're going to start a new activity,
which is defined in a class file.
0:50
Thus, we want the fourth option shown
here, that accepts the current context,
0:54
and a class as a parameter.
0:58
Remember that context is
really important in Android.
1:01
We discussed it briefly before, but
it is essentially the specific context or
1:04
environment within which
our code is running.
1:08
This code is in an activity, and
1:11
the activity class is a sub
class of the context class.
1:13
So we can use the current
activity as our context.
1:16
This is easily achieved
with the this keyword.
1:19
And in this case,
it's now referring to this current class.
1:22
There are other ways
to access the context.
1:25
For example,
we could type getApplicationContext,
1:27
which is a method available
in the activity class.
1:30
But let's undo that,
go with this, and now for
1:33
the second parameter, we want
the activity class that we want to start.
1:36
So we type StoryActivity and then we type
.class to reference the actual class.
1:41
When our app is actually running,
it needs the class object
1:47
rather than simply the name which
is why we use this class property.
1:50
Okay, next, just one more line of code.
1:53
We need to express this intention somehow.
1:55
This is often done using the method
from the activity base class called,
1:58
startActivity.
2:01
And look at that.
2:04
It takes an Intent as its parameter.
2:05
Type that and try it out,
and see what happens.
2:07
Okay, we can type a name again.
2:12
Hit enter.
2:17
Start the adventure.
2:18
All right, and we're taken to
our new blank story activity.
2:19