Collectors.summingInt

Collectors.summingInt is a static method in the Java Stream API that returns a collector which calculates the sum of a specified integer attribute in a stream of objects. It is commonly used in conjunction with the Stream.collect method.

Here's an example usage:

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Main {
    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

        int sum = numbers.stream()
                .collect(Collectors.summingInt(num -> num));

        System.out.println("Sum: " + sum);
    }
}

In this example, we have a list of integers `numbers`. We use the `stream()` method to create a stream from the list and then apply the `collect` method with `Collectors.summingInt` as the collector. The lambda expression `num -> num` specifies the integer attribute we want to sum. Finally, we print the sum which is the result of the `Collectors.summingInt` operation.