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Many collection types implement the list interface.

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For example, Array List implements the list interface.

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Linked list implemented as well, and there are other classes that we're not going to cover.

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So in this lesson, you're going to see polymorphism from classes that implement list.

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Open the folder for this lesson by following this path in your course resources.

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Now, list is an interface that defines methods a class must implement.

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The array list class implements this interface, it also implements a bunch of other interfaces, inherits

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from a class, but we don't care about that.

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Let's just focus on the fact that array list implements the list interface.

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Here are some of the methods that list the fines, this one should be familiar to you, size array list

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implements this interface.

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So we know the array list class overrides this method.

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You can go back here and call size from this array list.

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Here's another one is empty, and it follows that we can call is empty.

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Contains a list, definitely overrides, contains, because we've used it so many times before it.

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Anyways, you get the points, the array list class implements this interface, so it's basically signing

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a contract that it's going to override all of the methods inside this interface and it does.

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For example, we know our array list is going to be forced to override array.

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Let's start to Iraq, which returns an array from the array list.

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Now, linked list is another collection type, it also implements the list interface.

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Because linked list implements list, it also signs a contract that it's going to override all of the

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methods inside list.

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We can create a linked list collection in much the same way linked list that can store energy objects

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list to.

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Is equal to a new object of the limitless class.

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And because the linked list class implements the list interface, we know it's going to be forced to

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override all of these methods.

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So all the same, we can call at least to add a lot, a few numbers.

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We can call list to size.

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List that is empty.

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List contains.

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Listen to not Iraq.

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All right, so what's the difference between a relist and linked list, performance wise linked list

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is almost always the wrong choice.

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If you look at the documentation array list is usually faster.

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Array list offers a faster way of accessing elements because it has direct references to every element,

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whereas with a linked list, it has to go through every single element in the list until it gets to

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the element that you're trying to access.

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So it's a lot slower when you're trying to access values.

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In this course, we're going to stick to using a realist.

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Now, what's interesting is that remember that interfaces allow for polymorphism because array list

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implements the list interface.

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We can declare the object type list.

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Same thing here, we can declare the linked list as type list.

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Why is polymorphism important?

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Same reason as always, flexibility, if I declare this type list, then I can easily switch between

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array list and linked list.

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I like to just stick to our list now, all I want you to take away from this lesson is that array list

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and linked list can take the form of the interface they implement.

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Let's recap array list and linked list, implement the list interface.

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List is an interface that defines method's a class must implement.

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In other words, each class signed a contract to override every method inside the lowest interface.

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Each one of them overrides these methods in a different way.

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But in general, performance was linked.

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List is almost always the wrong choice.

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In this course, we're going to stick to using a realist.

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And because each class implements the interface, we can see polymorphism, you can declare the array

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list as type list Auris type array list, and you can also declare a linked list as its own type or

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type list.