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Being able to add or

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remove items from a list is certainly
a big improvement over arrays.

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00:00:06,000 --> 00:00:11,060
But in Java, lists can do a lot
more than just add or remove.

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Let's add a couple lines and
then try out the index of function.

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Let's create a new int
variable named samIndex.

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And set it equal to groceryline.indexOf,
and pass in Sam.

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Then, let's print out our samIndex.

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And perfect, Sam is an index 1.

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Now, let's see what happens when we
look for an object that doesn't exist.

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Instead of looking for
Sam, let's look for Pam.

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And if we run it, we get negative
1 because Pam is not in the list.

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Another thing to keep
in mind about indexOf

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is that it starts its search
from the beginning of the list.

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So if our list had two Sams in it, indexOf
would give us the index of the first Sam.

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Another important function
is the size function.

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You can think of it as the length
property of an array, except for a list.

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And since lists can change sizes, it needs
to be a function instead of a property.

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Let's add a couple lines and try it out.

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Let's sout, and
then print out groceryLine.size.

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Which gives us 2, nice.

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One more thing you should know about
lists is that you can use them

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with the for each loop.

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Let's add a couple lines,
and then type for.

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And inside,
let's make a string variable called name.

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Then add the colon, and
the name of our list.

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So for each string,
which we'll call name, and

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our grocery line list,
we're going to do something.

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And inside,
let's just print out the name variable.

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Great, that about does it for
the really important functions of a list.

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But I think it's worthwhile to
quickly point out a couple more

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in case you need them down the road.

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Let's add a couple of more lines to
the bottom of our main method, and

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then type groceryLine.,
and just leave it at that.

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We've already talked about most of these.

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So I'll skip past the first few and

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move on to the clear function, which
will remove all the items from the list.

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If we go a bit further down,
we'll also find the set function,

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which replaces the item
at the specified index.

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We've also go the two array functions,

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which returns an array containing
the same elements as our list.

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So if you've got a function
that takes in an array, but

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you've only got a list,
you're looking for the toArray method.

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Also, if you're curious what any of the
rest of these functions do, just select

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it, and then once it's in the code, use
Cmd or Ctrl+B to jump to its declaration.

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Then, depending on who wrote the code, you
might find some pretty good documentation.

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Hopefully that gives you a pretty
good overview of what lists are, and

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how to use them.

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As always if you have question head
on to the community and ask away.

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Until next time.