`ToLongBiFunction` is a functional interface that accepts two arguments and returns back a long. The interface contains one method: `applyAsLong`.


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

# `applyAsLong(T t, U u)`

This method applies the function to the given arguments and returns a long. This is the functional method of the interface.

## Syntax

```
long applyAsLong(T t, U u);
```

## Parameters 

- `T t` - the first argument.
- `U u` - the second argument.

## Returns

The method returns a long.

import java.util.function.ToLongBiFunction;

public class Main{
    public static void main(String[] args) {
        ToLongBiFunction<Integer, Integer> convertSumToLong = (i1, i2) -> i1 + i2;
        Integer i1 = 5;
        Integer i2 = 100;

        // calling applyAsLong method of the ToLongBiFunction
        System.out.println(convertSumToLong.applyAsLong(i1, i2));
    }
}

### Explanation
In the above code, we created a `ToLongBiFunction` interface that accepts two integer arguments and returns the sum of the two integer arguments as a long value. 

What is the ToLongBiFunction functional interface in Java?

`applyAsLong(T t, U u)`

Syntax

Parameters

Returns

Code

Explanation