All language subtitles for 1. Introduction to Lists

(bright music)
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(light typing)
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In this section,
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we're going to look at lists.
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The list is an abstract data type and in the next video,
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we're going to go over what an abstract data type is.
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So a list isn't a concrete data structure,
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it's an abstract data type.
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And when it comes to abstract data types,
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normally there's an interface involved
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and list is no exception.
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In Java, the lists that we're gonna look at in this section
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all implement the java.util.list interface,
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so that's what I have on this screen.
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Classes that implement the list interface represent
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an ordered collection also known as a sequence.
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There are quite a few classes that implement list.
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We're not gonna look at all of them.
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We are gonna look at a few.
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We're gonna look at array list.
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We're going to look linked list.
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We'll look at those two in this section.
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We're also gonna look at vector.
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There's also an abstract list class
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and an abstract sequential list.
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If you want to implement the list interface,
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you want to create a custom implementation
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rather than starting with list itself and implementing that,
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it's a good idea to instead extend abstract list
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and abstract sequential list
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because there are scoledo implementations
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of the list interface and so they kind of give you
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a head start and all you have to do is override the methods
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that you specifically want to implement
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if you want custom behaviour.
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So if you are going to implement a custom list,
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its a good idea to extend one of these two classes.
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So lets just look at a few of the methods in here.
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You'll see we have add, so we can add items to the list.
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We can check to see whether a list contains an object.
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We can get an object from the list if we have its index.
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We can find the index of an object in the list.
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We can check whether a list is empty.
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We can remove objects from the list.
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We can find out using the size method
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how many items are in the list
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and we can get the array that's backing a list
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and we're gonna see what that means
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in the next couple of videos.
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Now some of the classes we're gonna look at in this section,
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like array list, you've probably worked with before.
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Array list is a really popular class
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but we're gonna dig a little deeper.
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We're gonna actually look at some of the array list code
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to see what's going on under the covers.
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Okay, so when we're dealing with lists,
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we're dealing with an ordered sequence,
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so the data is organised sequentially
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just as it is in an array and we're gonna see
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in a couple of videos that a popular way to implement
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the list interface is to use an array.
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So let's move on now and take a quick look
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at what an abstract data type is.
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I'll see you in the next video.