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In this video we'll learn the three basic functions of a list: adding items, removing items, and accessing items!
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To get a better feel for how to use lists,
we'll need to use them in code.
0:00
Let's create a new project.
0:04
Hit Next and take it from a template.
0:09
And let's call that project, Lists.
0:13
Then I'll full screen my screen.
0:17
And hide the side panel,
then let's delete the comment.
0:20
And inside,
let's create a new list variable.
0:26
And notice that before we finish typing,
it's telling us something about lists.
0:30
For one, List green I tells
us the list is an interface.
0:35
Also thanks to the angle brackets, we know
that a list can take in a type parameter.
0:40
So instead of just making
this a list of objects,
0:46
let's make it a list of strings and
use Alt+Enter to import list.
0:50
Then let's name our list groceryLine and
set it equal to a new list of strings.
0:56
So = new List<String>() and ;.
1:03
But, of course, since list is
an interface, this won't work.
1:12
Instead, we'll need to use a class
that implements the list interface.
1:16
There's a few choices for this, but
1:22
almost always you'll want
to just use an ArrayList.
1:24
So let's just add Array right before List,
And then use Alt+Enter to import it.
1:27
Also, note that while we can use
an ArrayList on the left side as well,
1:34
we're better off leaving it as a list.
1:39
This way, later on if we ever decide
to use a different implementation of
1:42
the list interface, we can just update
it over here and be done with it.
1:47
Let's also use Alt+Enter to
shorten up the right side.
1:51
Okay, now that we've got our grocery line,
let's add a couple people to it.
1:56
On the next line,
let's type groceryLine.add and
2:00
notice that we've got a few ways
we can add items to a list.
2:04
We can add an item to the end of the list,
add an item at a specified index.
2:10
Add a group of items, or
add a group of items at a specified index.
2:15
Let's stick with the basic add function,
and
2:19
pass in Jerome for
the first person in line.
2:23
Then let's do this two more times,
and add Beth.
2:26
And let's also add Sam.
2:35
Finally, let's print out our list and
see what we've got.
2:40
Let's type sout and tab to bring up the
println statement and pass in groceryLine.
2:43
Then let's run the app, And nice,
2:52
we're able to see exactly what's
in the list just by printing it.
2:55
Okay, now let's say it's been something
like 30 minutes, and Beth has had enough.
3:01
She's got places to be so
she leaves the line.
3:07
Let's add a couple lines and
then remove Beth from our groceryLine
3:10
by calling groceryLine.remove and
passing in Beth.
3:16
Then let's print out
our grocery line again.
3:20
And run the app.
3:25
Perfect.
3:28
We removed Beth from the line.
3:29
You can also remove items by
passing in the index of the item
3:30
you'd like to remove.
3:35
So another way to remove Beth
would be to pass in index 1.
3:37
And if we run the app,
we get the same result.
3:43
Now that we've covered adding and
removing,
3:48
let's talk about how we
access the items in a list.
3:50
Unlike an array, where you put the index
between square brackets, with a list,
3:53
you just call the get function and
pass in the index of the item.
3:59
So if we wanted to create a new
String variable named jerome,
4:03
and set it equal to Jerome,
4:08
we'd set it equal to groceryLine.get and
pass in 0 for the index.
4:10
And if we print out our new
string variable, Called Jerome,
4:16
we should see Jerome.
4:21
Awesome, with that out of the way,
you're ready to get started using lists.
4:25
Just wait till after the next video.
4:30
There's a few more functions,
that you really should know about
4:32
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