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## Overview

**`UnaryOperator`** is a functional interface that represents a single-operand operation which yields a result of the same type as the operand. 

The interface extends the `Function` interface so the methods of the `Function` interface can be used on the implementation of the `UnaryOperator` interface. The interface overrides the `identity()` method of the `Function` interface.

The `UnaryOperator` interface is defined in the `java.util.function` package. To import the `UnaryOperator` interface, use the following import statement:

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## What is the `identity()` method?

The **`identity()` method** is a static method used to return a `unaryOperator` that always returns its input argument.

## Syntax

# 
#  Parameters 

The method has no parameters.

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## Return value

This method returns the input argument.

##
## Example

import java.util.function.UnaryOperator;

public class Main{

    public static void main(String[] args) {

        // Identity unary operator that accepts one input
        UnaryOperator<Integer> unaryOperator = UnaryOperator.identity();

        // argument
        int arg = 3;

        System.out.printf("UnaryOperator.identity(%s) = %s", arg, unaryOperator.apply(3));

    }
}

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## Explanation

- **Line 1**: We import the relevant packages.
- **Line 8**: We define an identity `unaryOperator` that accepts one input of integer type.
- **Line 11**: We define an integer value.
- **Line 13**: We test the identity `unaryOperator` using the `apply()` method on the integer value defined in line 11 and print the result.

What is the UnaryOperator functional interface in Java?

UnaryOperator is a functional interface in Java for operations yielding the same type result, extending Function. The identity method returns its input argument.

What is the UnaryOperator functional interface in Java?

Overview

What is the identity() method?

Syntax

Parameters

Return value

Example

Explanation

What is the `identity()` method?