**`ToIntFunction`** is a functional interface that accepts one argument and returns an `int` type result. The interface contains one method, i.e., **`applyAsInt`**.

The `ToIntFunction` interface is defined in the `java.util.function` package. To import the `ToIntFunction` interface, check the following import statement.
```
import java.util.function.ToIntFunction;
```

# 
## `applyAsInt(T value)`

This method applies the function to the given argument and returns the `int` type result. This is the functional method of the interface.

## Syntax

```
int applyAsInt(T value);
```

## Parameters 

- **`T value`**: This is the function argument.

## Returns

The method returns the result of type `int`.

## Code

import java.util.function.ToIntFunction;

public class Main{
    public static void main(String[] args) {
        ToIntFunction<Integer> convertSumToInt = (i1) -> i1 + 5;
        Integer i1 = 5;

        // calling applyAsInt method of the ToIntFunction
        System.out.println(convertSumToInt.applyAsInt(i1));
    }
}

What is the ToIntFunction functional interface in Java?

Accepts an argument, returns an int result, defined in java.util.function, method: applyAsInt.