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 unary and binary operator Functional interface.

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Let's go ahead and look into the unary operator functional interface.

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I am pressing the shift key twice, which is giving me the search everywhere option I'm going to search

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for unary operator.

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The unary operator is part of the Java.util dot function.

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Package.

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Now click on that.

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We take a look at it.

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This got introduced as part of Java eight.

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And then this is a functional interface, this functional interface extend the function functional interface.

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We discussed about function functional interface in one of our previous tutorial, a function interface

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which takes an input of one type and produces an output of other type.

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Let's go ahead and take a look at one of the example that we coded before.

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So if you take a look at the function student example here in this function student example, we have

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the input as list of students, but it returns a map of student of type of key string and then the value

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as double.

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Now, you might be having this question in your mind.

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So we have a function interface already.

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So under what scenarios I will use unary operator.

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Let's say you have a use case where the input and output are of the same type.

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Those use cases you can use unary operator functional interface instead of a function.

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Now let's go ahead and create the unary operator.

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Example.

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Unary operator.

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Temple.

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I'm going to make this class executable.

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Public static void Main.

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What I'm going to do is I'm going to declare a unary operator, unary operator, and it is going to

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take in a type called string.

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So basically the input and output of this unary operator is going to be string.

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The next steps.

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This string is going to.

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Perform a concat operation.

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Though I didn't give the.

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Variable name is Dot.

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Venkat is going to add a default string to it.

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That's it.

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I want to keep this example really simple.

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So in here, this unary operator is going to take in a type as string and it is going to return the

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type as string.

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Is that one?

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Re operator dot apply.

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When a pass a string as Java eight.

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So here it printed the value as Java eight default.

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Basically, it successfully applied this concat operation to the input that we passed.

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So this is all about unary operator.

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So keep that in your mind.

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Whenever you have a use case where the input and output are of the same type in those kind of use cases,

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you don't even have to use a function.

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You can use unary operator in those use cases.

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Let's talk about binary operator now.

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On a search for binary operator.

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The binary operator is also part of the java.util dot function package.

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From the name, we can say that it is going to act on two inputs and it is going to produce one output.

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So if you take a look at the binary operator, it extends the by function functional interface.

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So what is a by function functional interface?

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It takes in two input and then produces one output.

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We have coded the by function in one of the previous tutorial.

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Let's go ahead and take a look at that.

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Take a look at the by function.

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It takes a list of student and then it takes the second input as a predicate and it produces the map

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as an output.

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Go back to the binary operator example under what scenarios you will use.

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Binary Operator.

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That might be the question that will be running in your mind.

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So if the inputs and the output are of the same type, then in those kind of use cases we will use binary

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operator, binary operator as two additional static methods which are mean by and max by.

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Let's go ahead and code and explore all these methods.

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A step.

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I'm going to create the class called Binary operator.

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Example, want to make this class executable by adding the public static void main method.

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The next step is we are going to create the implementation for binary operator.

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I want to create a really simple use case.

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It's going to take in two inputs and then perform the multiplication operation on that and return the

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result.

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So integer.

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Next up is binary operator.

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Given a name now, it's going to take in two inputs.

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And then it produces one output, which is the multiplication of those two inputs.

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When does this?

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Binary operator does not apply.

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Pick come up for, though the result is going to be 12.

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There we go.

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We have successfully implemented the binary operator.

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Now let's take a look at some of the static methods that it has.

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One is the min by and max by.

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So let's explore and discuss more about it.

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The min boy accepts a comparator and the Max boy accepts a comparator.

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What we have to do is the first step.

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We need to create an instance of comparator.

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I'm going to create a comparator.

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The class level.

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I'm going to declare that one is in the static keyword because I'm going to use it in our.

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Main method.

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So in here it is going to take an integer.

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What this comparator is going to do, it is going to use the Compareto method, which is part of the

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integer class.

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It's going to accept to input a comma B because comparator requires two input and then it is going to

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perform a dot compare to B.

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So this is what is going to do.

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If we take a look at the comparator method, it compares the two integers which are passed to it and

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then it returns an integer again.

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Okay.

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What's the next step?

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The next step is I'm going to create one more instance of binary operator.

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And then I'm going to name this one as Max Buy because we are going to test the Max buy method as part

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of this one.

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So in here, the static method, right?

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So we will call it using using the binary operator class Max buy and then pass the comparator.

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Okay, so it should be comparator.

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The next step.

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How do we pass inputs to it?

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The way to pass the input is result of max by is.

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Bags by dot apply and pass the two integers.

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Four comma five.

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So since it's a max by function, it is going to return.

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What is the.

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Largest meaning greatest value out of the two.

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It printed the value as five because five is greater than four.

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Next we will implement the min.

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By that I'm going to name this one as min by.

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Then I'm going to name change the result text also to mean by and I'm going to use min by method here.

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There you go.

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If I run this, it is going to print.

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Paul over here.

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So here I'm still using the max buy dot apply.

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A copy paste error.

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This again.

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There you go.

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The result is four.

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So this is all about unary operator and binary operator.

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If the input and output types are the same, then we can use the binary operator and unary operator

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the place of function.

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With this we came to the end of this.