# 
#  Overview

The **`mapToInt()` method** of the `Stream` interface is used to return an `IntStream` that contains the results of applying the provided implementation of the [ToIntFunction()](https://www.educative.io/answers/what-is-the-tointfunction-functional-interface-in-java) function on the stream's items.

# 
#  Syntax
---

``` java
IntStream mapToInt(ToIntFunction<? super T> mapper)
```

---

# 
## Parameters 

- `ToIntFunction<? super T> mapper`: This is the mapper function that needs to be applied.

##
## Return value

This method returns a new stream.

##
## Code

import java.util.Arrays;
import java.util.List;
import java.util.function.ToIntFunction;

public class Main{

    public static void main(String[] args) {
        // define the list of integers
        List<Integer> integerList = Arrays.asList(10, 24, 54, 8,232);

        // Define the implementation of ToIntFunction interface
        ToIntFunction<Integer> multiplyByTwo = e -> e * 2;

        // apply the multiplyByTwo using mapToInt function and print each value
        integerList.stream().mapToInt(multiplyByTwo).forEach(System.out::println);
    }
}

What is the Stream.mapToInt() method in Java?

The Stream.mapToInt() method in Java returns an IntStream by applying a ToIntFunction on stream items.