1
00:00:00,470 --> 00:00:03,460
So now we have a way of
communicating with our users.

2
00:00:03,460 --> 00:00:06,960
However, our conversations seems
a little one sided, doesn't it?

3
00:00:06,960 --> 00:00:08,290
Let's see if we can't go ahead and

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00:00:08,290 --> 00:00:11,900
listen to what the person on the other
side of the screen has to say.

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00:00:11,900 --> 00:00:14,690
So what we've done thus far is all output.

6
00:00:14,690 --> 00:00:17,790
Now we're going to introduce
input into our application.

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00:00:17,790 --> 00:00:20,520
More specifically input from the keyboard.

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00:00:20,520 --> 00:00:22,640
Let's head back over to our workspace and
take some input.

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00:00:24,230 --> 00:00:27,950
Okay, so our first named variable
here is currently hardcoded.

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00:00:27,950 --> 00:00:30,290
Let's see if we can't make
it a little more dynamic.

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00:00:30,290 --> 00:00:33,160
Remember how we said that objects
like console have methods

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00:00:33,160 --> 00:00:35,010
that allow them to perform actions?

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00:00:35,010 --> 00:00:39,420
So far we've only seen one method, printf,
and that prints text to the screen.

14
00:00:39,420 --> 00:00:42,550
Well the same console object that
we've been using has another method

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00:00:42,550 --> 00:00:44,000
called read line.

16
00:00:44,000 --> 00:00:48,020
Just like the printf method prints text
out to the user, the readline method

17
00:00:48,020 --> 00:00:52,220
prints text out, and then it captures
whatever the user types afterwards.

18
00:00:52,220 --> 00:00:54,170
So it can be used to prompt the user for
their name and

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00:00:54,170 --> 00:00:55,560
then capture what they type.

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00:00:55,560 --> 00:00:56,780
Let's do that.

21
00:00:56,780 --> 00:00:58,960
So first let's remove the string.

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00:01:02,226 --> 00:01:03,910
And then let's type console.

23
00:01:03,910 --> 00:01:07,620
And then we can access its
methods by pressing a period and

24
00:01:07,620 --> 00:01:10,280
then we'll type readLine,
that's the name of the method.

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00:01:10,280 --> 00:01:16,160
And we'll call it double quotes, will type
what is your name, cuz that's the prompt.

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00:01:16,160 --> 00:01:21,470
Two spaces and then a quote, and
then we will end the parenthesis,

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00:01:21,470 --> 00:01:23,119
and we're gonna just leave
that semi colon there.

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00:01:24,250 --> 00:01:26,610
Okay, so let's take a look at this.

29
00:01:26,610 --> 00:01:29,400
So like we said,
the read line method gives us a string.

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00:01:29,400 --> 00:01:31,100
This is known as returning a value.

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00:01:32,210 --> 00:01:35,520
We know that we can call methods
on an object to perform actions

32
00:01:35,520 --> 00:01:38,730
while another feature of methods is that
they can return back information when

33
00:01:38,730 --> 00:01:39,990
they're done performing.

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00:01:39,990 --> 00:01:42,640
In this case this method
returns a value that we

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00:01:42,640 --> 00:01:45,250
then use to set our first name variable.

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00:01:45,250 --> 00:01:49,170
Just like before, we use that value stored
in the first name variable to write out or

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00:01:49,170 --> 00:01:50,950
formatted sentences.

38
00:01:50,950 --> 00:01:55,285
Okay, so we're gonna save our file,
then we are going to compile javac

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00:01:55,285 --> 00:01:59,205
introductions.java.

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00:01:59,205 --> 00:02:06,980
And there we're gonna go ahead and
type java introductions and press Enter.

41
00:02:06,980 --> 00:02:10,630
And it's gonna prompt us know and see
because up at the two spaces notice how

42
00:02:10,630 --> 00:02:13,532
the cursor is right there
right after the two spaces,

43
00:02:13,532 --> 00:02:15,710
that's why it's important to leave
the two spaces in the prompt.

44
00:02:15,710 --> 00:02:16,750
So we'll say, what is your name?

45
00:02:16,750 --> 00:02:19,590
And we'll put in Andrew and we'll see the
program run and you'll see that it puts

46
00:02:19,590 --> 00:02:22,930
Andrew in all the places where the first
name variable was just like before.

47
00:02:22,930 --> 00:02:28,120
Now the program has dynamically changed
based on input from the user, nice.

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00:02:29,390 --> 00:02:33,580
We've now learned how to take input from
a keyboard in a command line program and

49
00:02:33,580 --> 00:02:35,710
then output a formatted version.

50
00:02:35,710 --> 00:02:39,930
This combination of input and
output is often referred to as IO.

51
00:02:40,930 --> 00:02:44,180
In fact, if you look at the top
of the code that we just wrote,

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00:02:44,180 --> 00:02:48,700
we're importing the console
type from the java.io package.

53
00:02:48,700 --> 00:02:52,650
Java packages are used to bundle
related functionality and programs.

54
00:02:52,650 --> 00:02:55,630
Building and using packages is
a more advanced concept but

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00:02:55,630 --> 00:03:00,200
I just wanted to point out here that that
new term that you just learned about IO

56
00:03:00,200 --> 00:03:02,720
is already right there in the statement
that we had previously ignored.

57
00:03:03,820 --> 00:03:10,110
Congrats, you now know how to send output
receive input, store and use variables.

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00:03:10,110 --> 00:03:13,430
You will use these concepts in
almost every interactive application

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00:03:13,430 --> 00:03:14,760
that you'll write.

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00:03:14,760 --> 00:03:18,160
Now since they're such important concepts,
let's end this stage with an exercise.