15- The BinaryOperator Interface

Jul 01, 2026 03:59 · 3:15 · English · Whisper Turbo · 2 Høyttalere

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Early in this section we talked about this package,

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java .util .function.

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This is where we have all these functional interfaces in java.

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I told you that the list may appear overwhelming,

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but the concept behind this list is actually very simple.

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All these interfaces fall into four categories.

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We have consumers,

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suppliers,

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functions,

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and predicates.

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So all the interfaces you saw are specializations of these four

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types of functional interfaces.

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Now in this video we're going to talk about a special type of function called binary

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operator.

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This addition operator we have here is an example of a binary operator

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because it has two operands and returns a single

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result.

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Now we can represent this concept,

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this operation,

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using the binary operator interface.

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Now as you can see,

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this interface extends the bifunction interface,

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so the binary operator interface is a special type of function.

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It's a function that takes two arguments of type T and returns a

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result of type T.

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Now just like the other interfaces,

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we have primitive specializations of this interface.

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For example,

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we have int binary operator that takes two primitive integers

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and returns an integer.

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Now let me show you how to use the binary operator interface.

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So let's declare a binary operator of integer,

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call it add,

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and set it to a lambda expression like this.

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Here we need two parameters,

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so we should wrap them in parenthesis.

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We can call them a and b.

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then add the lambda operator and return a plus b.

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As simple as that.

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Now,

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because the binary operator is a special type of the function interface,

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here we have the apply method,

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so we can pass 1 and 2,

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get the result,

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and start over here.

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Now in this example,

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we are working with primitive integers,

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so these primitive integers have to be auto -boxed inside

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instances of the integer class.

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So if you're dealing with a large number of primitive integers,

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it is more efficient to use the int binary operator

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interface.

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Okay?

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Now let's make this more interesting.

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Let's say we want to represent this operation.

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We have two arguments,

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like a and b.

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First we want to add them together,

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so a plus b,

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and then we want to get the square of the result.

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Now to model this,

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we should have two small functions,

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each representing one operation,

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and then compose them.

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So here's the first function.

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Now let's create a function to get the square of a number.

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That is pretty easy.

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So function of integer and

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integer.

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So this function takes an integer and returns another integer.

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We call it square and set it to a lambda like this.

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A goes to A times A.

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We can use function composition to represent this

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operation.

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So first we add these numbers and then we

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square the result.

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Now if you print the result we should see 9 there

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you go So this is how we can use the binary operator interface in

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Java

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