Hello, guys, welcome back to the next tutorial. So in going forward for the Java collections framework, we're going to learn about sets. Sets is again, one of the collections that stores elements inside it like any list in the list that we already looked at before lectures. But the unique property of sets is that it stores only unique elements. And I'm just going to display that I'm going to do a demonstration of that what I mean by unique elements. So let's quickly open the eclipse.

And go ahead did that. So I have a class called sets demo pair set already. So let's define a set. So the index is set. And we already know for the collections framework, mostly in ArrayList, linked list and set pretty much everything we have to first define that what kind of elements that we want to store is that an integer or a string or a different type, so we want to mention that before. And so I'm going to mention its thing right now.

And give it an As a small set, so this is a variable name, reference name. It's not from the class. So we'll just keep it set to keep it simple. So now new set. And we want to again, give the type here. So string and parenthesis and the code.

So it gives us this thing. So you want to just import set from Java dot util, right? So once we import it, you're all set to go. Right. So again, it said, set right, so what we're gonna do here is we're gonna say hash set. So this is one of the types of the set that we want to do.

So let's import the hash set. So I'm just gonna explain after a while that what kind of sets are available. So let's first just take a look at the hash set, which is the simplest and mostly use one. And let's go ahead so what we can do with the set is we can just add values, so add. So let's add a group of cars as you always do it. MW said dot add rd.

Right? And Formosa dot add. Let's call it on. All right, so we have three elements added to our set. So now let's again quickly define a list. So list of types string, right?

And list equals to new array list. Again, the type should be string and parenthesis, right. So come on, sir. Oh, I'm just going to import it from Java utils. And it's just going to import everything right. So we're going to define the same thing with we're just going to add the same thing.

Let's start add BMW. Let's start add. Oops, not this. some reason it's just sometimes tries to become more smart right before So already, right? Let's start, add, and Connor. So similar way, the way we define list the same ways we can add stuff to a set as well.

Now let's talk about the difference. So in my list, what I can do is I can add an element again, right? If I say, Honda, I'm adding the Honda again, right? But let's try to do that in set. And here you can see right, you can see I added Okay, cool, fine. So now let's print it out.

So see, so let's print out our set. And here. Let's print out the list right. So what we're doing is we're adding all these four elements in the set and the same elements in the list, and we're just printing it out. So let's save it and run the code. Once again, going to notice here guys is that the first one is the set which is Audi, BMW Honda.

The stuff you'll notice here is the Honda only appears one time. But in our in our list, it is BMW, Audi, Honda, and Honda. Which means Honda appears twice because we added twice, right? Same thing we did with the set as well, but it only appeared once. So that is what I was talking about. Vanessa set only stores unique set of elements.

So only unique elements. If I try to add the same element, again, it's not gonna add it, it's gonna say I already have it. So no need. So that is the unique property of set. And that's where you want to differentiate when to use and when to use less. And it's sometimes it's common question as well in any fields that when do you want to say, when do you want to use sets?

And when do you want to use less? So this is one important thing. Right, cool. So let's go ahead and see how do we iterate over the sets right let's let's try to take a look at that. So now I have a set define already, so we can use for each loop. So far.

And we need to define the type of the elements that be stored in the set. So stray. And the one we're going to use is maybe item, anything we can use here, right? This is just a variable that's going to be used to iterate over the set. And our name of this step, right. So this is the name that we are using here, to iterate over right?

And then how to loop up their brackets. And we can just iterate over these things, so we can just print them out. So let's print the item. That's pretty much, right. That's how we trade with the SEC. And the code.

The first thing is already we're printing out all this stuff. And this is the iteration Audi, BMW, Honda. This is how we trade over the set. You guys might have noticed that it doesn't appear in any order, right? We added in the order of BMW, Audi and Honda, but it shows our a BMW Honda. So that's what the thing about the house That is that's clear I wanted to differentiate.

So I said it does not maintain any Order. Order. So that's what the thing about assets but it's the fastest because it doesn't have to maintain any order. It doesn't have to do any extra processing. That's why it's faster, then there are more type of sets when it's like link faster. So, it maintains the order in which the elements are added.

And the other one is the other important one is reset. It maintains sorry, the typos, typos of their maintains the natural sorting error. So natural sorting Order. So what do I mean by natural sorting is one, two, right? Three, and like that. And for the strings, it's a like alphabetical, right?

Alphabetical. So that's what the ordered maintenance. Same way we can define these sets, there's no difference in these index just we want to change the name. So set, maybe we can see linked hash. Set something like that, right? Or maybe just, let's not give it a big name, just say l. Edge.

Set. And here instead of hashtag. We want to say, link, hash set, right? And we want to import again, import linked hash set from Java dot util. And in similar way, we can define set string. And let's say tree set, sortie set equals a new tree.

Set, right. And then string is the type of parenthesis. And that's about it. So we just want to again import the stuff. So import from Java dot util. and other similar ways, we can just add stuff up there as well in the tree set and all those things, it's exactly the same.

Or maybe just I can, I can pretty much quickly show you that we can add stuff like that and just add stuff here as well. And let's remove this extra one, we don't need it again and again, right. So what we want to do here is change this two l edge, maybe a headset, right? and copy this pair and this is a T set. Again, just copy this, change these right? So these are just going to maintain the order.

So what I can do is I can just create show you these things just by printing out, right? So let's just come in this one. And let's command the list also. So the list is committed. So now we are only going to print these things. So let's just say C. So, and this is the linked one.

And let's see. See, so here, again, just copied, right. So let's call this one. So we know that what we are doing, we know where we are printing which one. So just just comments to understand all these. So instead of saying, set here, we can just say l at set.

And we can say here, t set, right? So let's run the code quickly and we're gonna see what's happening. So the first one is our Audi, BMW, Honda, which is the hat one. Second one is BMW, Audi, Honda, which The order that we added right, BMW, Audi, Honda, in the second The last one is she said is it's alphabetical order a BMW Honda, which is the alphabetical order the natural sorting order. So this one is also showing the hash one if you see. So let me just put that thing up here.

And so this you guys know. So when I'm printing this one out, the hash one it's also showing me right now Audi, BMW Honda, same as the preset Audi, BMW Honda, but this is not guaranteed, it can change anytime. So that's why we we cannot rely on the high said that it's going to maintain any natural sorting or any other order. So just just be aware of that. Just be careful of that. So you want to know that which one I'm using At what time?

So again, this is also very important interview question sometimes that what is the difference between the third the link has said the hashtag and the tree set. So that's difference you want to mention that which are maintains water and which is faster, which is not faster. So hazard is faster because it doesn't have to do anything, then tree said is not as fast as hazard because it has to maintain a natural sorting order. So that's pretty much it guys for this one. I would just say practice a lot for this one. Define your own sets, come up with something and do a little bit practice.

Stay tuned for the next lectures guys. Thanks for attending this one.