WEBVTT

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Hi everyone.

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Welcome back to this tutorial.

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In this tutorial we will code and explore the orals method, the get method and the orals throw method

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that are part of the optional class.

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The first step is I'm going to create a class called Optional.

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Or else.

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Example.

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And let's make this class executable.

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The adding public static void main method.

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So the methods that we are going to explore are.

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Arrows.

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And then get.

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And then else.

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So.

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The first method that we are going to explore is a orals method.

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I'm going to create a method.

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Oblique static.

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And this method is going to return a string.

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And it's going to be optional or else.

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Right.

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So what is the first step?

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We need an optional object.

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I'm going to use optional dot optional label.

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I'm going to make use of the student database class as part of this tutorial.

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Student base dot students supplier dot get this is going to give you a valid student.

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So if you go to the students player, this will give you a student who has the name as Adam grade level

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as two and the GPA as 3.6.

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And the gender is male.

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And these are the activities that Adam is participating.

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So since we do a lot of nullable, we have seen this in the previous tutorial.

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This is going to return you an optional object of type student because the input to the the input to

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the of nullable method is a student object.

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Let's give it a name.

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Student optional.

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So there we go.

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We have the student optional.

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The next thing is we are going to explore the method, right?

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So I want the name of the student.

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That's the use case, which I'm trying to achieve here.

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What would I do?

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Optional.

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A student optional dot.

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I'm going to use a map method which we explored in our first tutorial.

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We'll be exploring more on the map in the future tutorial.

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For now, we are going to use a map method in the student.

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We want the name right?

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So we'll give Student Colon.

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Colon.

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We are going to use the method reference syntax here and then give the get name.

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In the place of this, you get access to all these different methods that optional supports.

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In here we are going to use the orals.

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What I'm going to do, I'm going to return default under what scenario this code will get executed.

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I will explain that in a moment.

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So this is going to be string.

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Name equal to this and return name.

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So in here we get the student that is going to map the student name.

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So if there is a valid value, then it is going to return the actual name.

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Let's run this and check the result.

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So what I'm going to do.

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I'm going to do System.out.println and then call optional.

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Else Right.

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Let's run this and check the result.

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The result is going to be Adam.

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So under what scenarios?

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It would return default.

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So I'm going to comment this line.

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Or I want to come on these two lines.

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What I'm going to do, I'm going to do.

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Thus an optional dot of nullable and then I'm going to pass null.

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If you pass null, we all know this is going to return the optional dot empty.

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So it's going to return optional dot empty object.

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Basically option empty.

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Right.

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So when it checks this, it is going to try to map the student object and try to get the name.

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But since it is empty, it won't be able to execute this line and then it is going to execute the else

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and return you the default as a result.

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So I'm going to run this example.

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There you go.

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We got the default as a result.

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So if you want to return a default values in your use cases, if the actual value is null in those kind

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of scenarios, you can use the or else method.

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Okay, let's go ahead and explore the next one, which is the get.

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I'm going to copy the same method.

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This method is also going to return you the string, but it is going to be or else get.

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And I'm going to use the same code here, whatever we had.

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And then what we are going to do.

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We're going to do the same logic not changing anything here.

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That this is going to be orals get So orals get if you take a look at it, it it accepts a supplier

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instead of a simple string, it is going to accept a supplier.

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So the supplier we know the syntax for supplier supplier does.

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I'm going to use a lambda syntax here.

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Supplier doesn't take any input, but it is going to return you an output, right?

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That's what supplier is for.

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So here I have created the simple lambda implementation of the supplier, which doesn't take any input,

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but it is going to return you the output.

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So this is all about supplier.

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This is all about sorry, optional or else get method.

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It's going to return the name as an output.

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So go ahead and run this.

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I'm going to name it accordingly.

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So this is orals.

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Get right.

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This is Aurel's get.

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And this is Aurel's.

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Gonna run this and check the result.

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So the result is going to be default.

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Here what's happening?

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So here, if we take a look at it, we are not calling this.

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That's the reason why it printed default because I'm expecting the name a student because I'm supplying

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a valid student here.

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Let's run this and check the result.

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We take a look at it.

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The result is.

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Adam Right.

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So under what scenarios this would return default if this is of.

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Type.

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Now, in that case, it is going to call this or else get method and the supplier is going to return

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the default as output.

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There you go.

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Both are printing the same result.

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So the only difference is that this accepts the actual string.

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This accepts a supplier.

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That's the only difference between Orioles and Orioles get.

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Now let's go ahead and explore the Orioles throw.

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That's the next one, right?

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When I record this.

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There's going to be or else.

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Row and in here.

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Let's go.

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This one.

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I'm going to copy this line of code where it's going to return a valid student first, and then we'll

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go back to the null student.

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And then it's going to be the same code.

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In the place of orals get we are going to use orals through orals through is again a it is accepting

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a supplier.

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Right.

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What we will do.

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Will implement the supplier using the lambda expression.

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And then this is going to return a runtime exception.

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We all know Throw is going to.

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Throw an exception back to the caller.

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Right?

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That's what it is.

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So.

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New runtime exception.

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And I'm going to give let me put this below so that the code will be clear on the screen.

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It is going to return you the value as no data.

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Available.

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Now let's run this first.

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Basically, it is going to return the name of the student and then we'll pass the value as null in here.

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It is going to return the runtime exception return name.

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So.

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This one.

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Aurel Stroe.

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Copy this and put it here.

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The method that we are going to call is optional.

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Stone.

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Let's run this.

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In this run, it is going to return you the actual name of the student, because we are getting the

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name of the student from the student database.

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So it printed this.

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Now what I'm going to do, I'm going to return.

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I'm going to pass null In this case, it is not going to execute this code.

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It is going to execute the throw code.

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Let's go ahead and run this one.

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If you run this one, this gave you the exception back.

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So basically, Java dot Lang dot runtime exception.

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No data available in your use case.

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If you feel like if there is no data available, then I want to throw the exception back to the caller

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and those kind of use cases you would use or else throw.

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If you want the default value in those kind of use cases, you would either use a or else or else get.

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So this is all about the or else or else get and or else throw methods.

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With this, we came to the end of this tutorial.

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Thank you for watching.