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Welcome back.

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And this video, we are going to look at the Elvis operator and not null assertion operator and in order

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to do so, I.

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First of all, start by commenting odd name here because we just did and we saw how it works, right?

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But now what I want to do, I want to assign our Nullarbor name to a nonviable variable.

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So this value here should be a null Nullarbor, right?

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But I have another notable variable here called multiple name, and I need to assign it to this variable.

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So sometimes you have this situation and you can't get around it.

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So what you can do is you can use the.

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Elvis operator in order to either assigned a value that is within that Nullarbor name variable, so

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let's say the verbal has a name in there.

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And otherwise, it's just going to have this default value.

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So you use question mark colon in order to say, OK, if Nullarbor is empty, then please use my default

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value that I have here otherwise used to value that is in the Nullarbor name.

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So now if you print that name, we will see that it should say in this case, Dennis, because the Nullarbor

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name is in fact not now.

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So there we are.

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Name is Dennis.

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But now let's say we make Nullarbor name, though, and we run this again.

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Then we see name as guest.

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OK, so if the value is now, then it's going to take the default value.

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So this one, this question mark colon here that we're using is the Elvis operator.

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All right, the next thing that I want to use is to not know Assertion Operator, which is the double

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exclamation mark operator that converts and gullible type to a non null type and throws a null pointer

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exception if the noble type holds a null value.

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This is risky, and you should only use it if you are 100 percent certain that there will be a value

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in the variable.

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So let's use it here.

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I'm going to say noble name double exclamation mark thought to lower case.

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OK, so there is this.

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Method call to lowercase and it's going to put everything to a lowercase value.

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So instead of guests, it's going to say guest, for example.

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All right.

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So this here in our case will create the null pointer exception because we are really forcing it.

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And it's our own mistake because we didn't make sure that knowable name is in fact, not now.

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So if you can see here, I'm getting a call in my pointer exception in line 17.

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So in this line here.

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And this has to do with.

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Multiple name B no.

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So you can see it is now at this line, so that's why we get this error.

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So now if it's not now because it was the Santa Anas here and we never change it to, no.

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So if it's not now it's going to print Dennis and lowercase.

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And there we are.

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Name is Dennis.

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So now if we print that.

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Notable name, and we get rid of this print statement that we have before now to just print Dennis with

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a lowercase.

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So there we are.

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Dennis.

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All right.

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So now you have seen how no pointer exception works and how you can force one.

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You also have seen how multiples work in Kotlin.

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And there's one last thing that I want to show you, but it will not make sense.

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You know, it will make more sense once we get into objects and variables.

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But I just want to very quickly show you that you can use the safe call operator in a chain.

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So here we are using a chain safe call, so to speak.

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So let's say we have a class called user and we create an object of it.

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There is a way for so the user can have a wife, which is also of a class or of a type.

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And then this wife has an h.

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So what we can do is we can use a chain safe call here, for example, checking if the user is empty.

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And then also checking if the user's wife is empty.

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So if it's null or not.

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Okay, so if that's the case, then assign a value of zero.

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So as I said, this only makes sense once you understand the concept of object oriented programming.

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But if you come from another programming language, that will make now sense already.

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But otherwise, I think it makes sense to go into object oriented programming, which we will do in

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the next video.

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So the next thing that we're going to look at is actually classes and objects.

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And this is a little much for now, but I just wanted to show you this in order to complete this section

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or this lecture for multiples in Portland.

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All right.

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So I'd say, let's go to the next video where we're going to check out object oriented programming and

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how to create our own classes.