This course will be retired on July 14, 2025.
Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll
Well done!
You have completed Java Lists!
You have completed Java Lists!
Preview
In this video we'll talk about some other important functions of Lists and see how to use them!
This video doesn't have any notes.
Related Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign upRelated Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign up
Being able to add or
0:00
remove items from a list is certainly
a big improvement over arrays.
0:01
But in Java, lists can do a lot
more than just add or remove.
0:06
Let's add a couple lines and
then try out the index of function.
0:11
Let's create a new int
variable named samIndex.
0:14
And set it equal to groceryline.indexOf,
and pass in Sam.
0:18
Then, let's print out our samIndex.
0:25
And perfect, Sam is an index 1.
0:31
Now, let's see what happens when we
look for an object that doesn't exist.
0:34
Instead of looking for
Sam, let's look for Pam.
0:39
And if we run it, we get negative
1 because Pam is not in the list.
0:45
Another thing to keep
in mind about indexOf
0:53
is that it starts its search
from the beginning of the list.
0:55
So if our list had two Sams in it, indexOf
would give us the index of the first Sam.
0:59
Another important function
is the size function.
1:07
You can think of it as the length
property of an array, except for a list.
1:10
And since lists can change sizes, it needs
to be a function instead of a property.
1:15
Let's add a couple lines and try it out.
1:21
Let's sout, and
then print out groceryLine.size.
1:23
Which gives us 2, nice.
1:30
One more thing you should know about
lists is that you can use them
1:33
with the for each loop.
1:36
Let's add a couple lines,
and then type for.
1:38
And inside,
let's make a string variable called name.
1:42
Then add the colon, and
the name of our list.
1:47
So for each string,
which we'll call name, and
1:51
our grocery line list,
we're going to do something.
1:55
And inside,
let's just print out the name variable.
1:59
Great, that about does it for
the really important functions of a list.
2:06
But I think it's worthwhile to
quickly point out a couple more
2:11
in case you need them down the road.
2:14
Let's add a couple of more lines to
the bottom of our main method, and
2:17
then type groceryLine.,
and just leave it at that.
2:20
We've already talked about most of these.
2:24
So I'll skip past the first few and
2:26
move on to the clear function, which
will remove all the items from the list.
2:28
If we go a bit further down,
we'll also find the set function,
2:33
which replaces the item
at the specified index.
2:37
We've also go the two array functions,
2:40
which returns an array containing
the same elements as our list.
2:43
So if you've got a function
that takes in an array, but
2:47
you've only got a list,
you're looking for the toArray method.
2:51
Also, if you're curious what any of the
rest of these functions do, just select
2:55
it, and then once it's in the code, use
Cmd or Ctrl+B to jump to its declaration.
2:59
Then, depending on who wrote the code, you
might find some pretty good documentation.
3:07
Hopefully that gives you a pretty
good overview of what lists are, and
3:15
how to use them.
3:19
As always if you have question head
on to the community and ask away.
3:20
Until next time.
3:25
You need to sign up for Treehouse in order to download course files.
Sign upYou need to sign up for Treehouse in order to set up Workspace
Sign up