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Welcome back.

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So let's look at one more collection that is going to be the set.

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So that is a type of collection that eliminates duplicate data.

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This collection is unordered, which means the elements are not sorted.

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The midtable class is set off while the mutable types are mutable set off.

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And then there's also a hash set off.

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So let's look at an example here.

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So first, I'm going to create this fruit's example, which will be a set of, for example, orange.

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Then you have Apple Grape.

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And finally, another Apple while we're at it.

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So now let's go ahead and print the size of the fruits set.

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So here?

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Print size, like so let's run it.

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And you will see that at this press three.

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So what's up here?

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Well, that is because our orange or apple and our grape are the only unique items inside of the set.

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It ignores this apple.

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Now let's add mango in here, for example, as well.

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And I'm going to put that right there.

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Mango.

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Very tasty.

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So we have orange, apple, mango grape and another apple.

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Now you could go as far as to add another orange.

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And what you will see is that you still get an while.

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This time you get four because we had the mango, but the apple and orange, the duplicates, so to

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speak, they are ignored.

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They are not taken into consideration.

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Now the cool thing is we can sort this list so we can, of course, also display fruits.

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So let's run this real quick.

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We'll see orange apple mango grape.

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So it ignored all of the additional details, and now we can also sort it by using two sorted set.

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So that's a very cool feature.

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So let's do that and you see Apple Grape, Mango Orange, so it's sorted it alphabetically.

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Now, the problem with this set is that it's not mutable.

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So let's go ahead and create a mutable list.

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So I'm going to call this one new fruits, and it will be a fruits to mutable list.

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So now this time we are converting our fruits into a mutable list of fruits.

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And now we can go ahead and use new fruits in order to add items to it.

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So, for example, a watermelon would be a very good addition to this.

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And then let's add another beautiful fruit that would be a pear.

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Like, so OK.

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And then let's print those.

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So print new fruits and let's see what we're going to get.

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And we see we have Apple Grape, Mango Orange.

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This is the first entry, this is this print statement on let me get rid of it in order to make this

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look a little smoother.

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We see orange, apple, mango, grape, watermelon, pear.

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OK, so it added those entries for us.

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We want to access a particular fruit in your list.

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You can go ahead and just use the element pat.

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And then the number that you want to have.

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So new fruits element at four.

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Let's see what's going to happen there and we see we get the watermelon because the watermelon at this

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point is at the index four, which means it's the fifth fruit because we have orange, apple, mango

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and grape.

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And then we have the watermelon.

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And that's index four because oranges at zero, apple at one mango, two grape at three watermelon four

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and pear at five.

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OK, now let's look at maps, OK, and we're not going to look at Google Maps or so, but we're going

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to create a map of where a map list of kind of collection.

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So Map is a type of collection that holds data in the form of a key value pair, and the map keys are

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unique and hold only one value for each key.

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So let's look at that.

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So we have days of the week, for example, and this time we're going to use a map of here.

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So this will be a map of one to Monday, for example.

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That's how you can map.

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Very easy way.

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Pretty cool.

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And here you need to have the empty spaces.

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So one to Monday, then two to four example Tuesday at three to Wednesday.

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So.

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I have now connected the numbers to the dates, and that means that this key, this is the key is connected

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to the value of Wednesday.

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The key one is connected to the value of Monday.

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So this key can only be existing once each key only exists once.

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So this is a map.

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But in other languages, this is also called a hash map or a dictionary.

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So depending on which programming language you're looking at, it just has different names.

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And then we can now go ahead and, for example, access a particular item or print days of week at position

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two, for example, would give us Tuesday.

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OK, so here we're not talking about the index, but the actual key.

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OK gets the key value and not the index.

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So let's run this and we will get the Tuesday entry because it is connected to the key of two if you

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want to loop through your items inside of a map.

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You can just go ahead and use for loop again, saying key in days of week dot keys.

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So now we're going through the individual keys and let's print.

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The key is to and then.

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The days of week dot.

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Well, in this case.

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The square brackets key and what this will give us, it will tell us what the key is and it will tell

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us the item that it is connected to.

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So this is the value that it's connected to.

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And here I'm using numbers to strings, but this could also be strings to, for example, objects.

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So you're not limited here.

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It's what gives you a lot of freedom here.

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So let's run this and see.

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One is to Monday to is to choose two entries to wed.

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So just a quick example of using our fruit data again.

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So here, data class fruit, which contains the value of name, which will be a string and then price,

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which will be a double.

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OK, so we have this beautiful fruit now, this fruit class, and now we could go ahead and say fruits.

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It's going to be a map of this will be fruits map.

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Let's call it like this.

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So that is unique map of.

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And then I connect, for example, one to my fruit, which is going to be grape and has the price of

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two point five.

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And then we have to assigned to fruit that will be mine actually here.

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You could even go ahead and use not grape, but favorite fruit, something like this favorite.

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And this would be OK.

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And here the fruit would be.

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Apple, even though I love apples and it has the price of.

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One Euro 1.0 euro in order to press to be precise.

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OK, so that will be our map of.

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And me find a good point to set the brake.

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So you see, we have this fruits map of where our key this time is a string and the value is an object.

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In our simple example here, our key was a number and the value was a string.

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So you can make whatever connections you want to have here, which is why maps are so powerful.

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Now, if you want to make changes, you need to make it a mutable list.

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So here I can just go ahead and change that to all new days of week or new day of week.

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And that will be days of the week.

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OK.

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And I'm going to make it the mutable map, so to mute a mob and now I can use the new days of the week

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to assign, for example, at the position four I can add.

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First day.

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And then at position five, I could add.

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Friday.

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And so forth.

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OK.

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And you can now sort her map by using the two sorted map method.

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So here, Brent new days of week dot to sorted map out this well sort of map for us.

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Let's run this real quick and we can see we have the sorted map and actually we have another print statements

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somewhere, which makes this a little more difficult to read.

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I believe this one.

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So let's get rid of this and run it again, and we can see now it's sorted.

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It's Monday, Tuesday, Wednesday, Thursday, Friday, and it's sorted by its key.

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So just like other collections, MEPs also have a bunch of different methods that you can play around

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with.

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So I would really recommend that you just go ahead and use to dot operator and just give yourself some

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hints.

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OK, so what you can do here, for example, it doesn't have an ad method, but it has other methods.

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So here, if you press the dot key, you can see there are a bunch of methods.

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In my case, the idea seems to be broken, so I'm going to fix that.

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OK, so that's it for this video.

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See you in the next one.