2- Overview of Collections Framework

Jun 20, 2026 07:45 · 3:08 · English · Whisper Turbo · 2 Højttalere

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Forelæsningsindeks

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S… Speaker 1 (2- Overview of Collections Framework)

Let's start this section by a brief overview of what we have in the collections framework.

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So the green boxes you see here are interfaces and the blue

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boxes are classes that implement these interfaces.

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Now don't worry about memorizing any of these,

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we're going to get back to this slide several times throughout this section.

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So at the top of this hierarchy,

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we have the iterable interface.

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This interface represents an object that can be used in a for each

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statement.

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So if we implement this interface in our generic list class,

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we'll be able to use it in a for each loop.

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I'll show you how to do that later.

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S… Speaker 1 (2- Overview of Collections Framework)

Below that we have the collection interface.

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This interface extends the iterable interface and adds additional

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functionality.

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It represents an object that can act like a container or a collection

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of objects.

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Now here's a question for you.

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What are the capabilities that we need in a collection?

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we should be able to add an object to a collection,

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S… Speaker 1 (2- Overview of Collections Framework)

we should be able to remove an object,

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S… Speaker 1 (2- Overview of Collections Framework)

we should be able to check for the existence of an object and so on.

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S… Speaker 1 (2- Overview of Collections Framework)

So these are the operations that the collection interface declares.

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S… Speaker 1 (2- Overview of Collections Framework)

If you search for Java collection interface,

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on this page,

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you can see all the operations that this interface declares.

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S… Speaker 2 (2- Overview of Collections Framework)

For example,

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we have add for adding an object,

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we have add all,

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we have clear and so on.

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Now, below this collection interface,

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we have three sub -interfaces,

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S… Speaker 2 (2- Overview of Collections Framework)

list,

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queue,

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and set.

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Each of these again inherits all the capability declared in the collection

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interface and add something extra.

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For example,

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the list interface allows us to work with an ordered collection and

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access objects using their index,

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just like how we can access an object by its index in an array.

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Now,

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we have different implementations of this interface in the collections framework.

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The one that you would be using most of the time is the ArrayList class,

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which is an implementation of a dynamic array.

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S… Speaker 1 (2- Overview of Collections Framework)

So internally,

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it uses an array to store objects.

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S… Speaker 1 (2- Overview of Collections Framework)

If the array gets full,

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it will automatically resize the array.

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We have another implementation called linked list,

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which is based on the linked list data structure.

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S… Speaker 1 (2- Overview of Collections Framework)

The explanation of linked lists goes beyond the scope of this course.

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S… Speaker 1 (2- Overview of Collections Framework)

I've covered them in detail in my data structures and algorithms course.

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So we have two different implementations of the list interface.

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Again,

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most of the time you would be using the array list class.

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The queue interface also extends the collection interface and provides additional

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operations for working with a queue of objects.

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We use queues in situations where we have a resource that can be shared

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amongst many consumers.

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A good example of this is the printer at your office.

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Different people can print different papers at the same time,

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but a printer is not going to be able to print them all simultaneously.

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So each job should go in a queue.

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The printer will then take these jobs one by one and process them.

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S… Speaker 1 (2- Overview of Collections Framework)

Now in the collections framework,

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the class that implements the queue interface is called priority queue.

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We're going to look at that later in this section.

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And finally,

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we have the set interface which represents a collection without duplicates.

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The class that implements this interface is called high set.

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So that was a very basic overview.

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Throughout this section,

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we're going to explore each of these building blocks in detail.

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