Class Name	Data Type	Introduced In	Package
IntSummaryStatistics	int	Java 8	java.util
LongSummaryStatistics	long	Java 8	java.util
DoubleSummaryStatistics	double	Java 8	java.util

Each of these classes provides:

• getCount() – number of elements
• getSum() – total sum
• getMin() – minimum value
• getMax() – maximum value
• getAverage() – average value

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

public class SummaryExample {
    public static void main(String[] args) {
        List<Integer> numbers = Arrays.asList(10, 20, 30, 40, 50);

        System.out.println("------------------------------");
        IntSummaryStatistics stats = numbers.stream()
                .mapToInt(Integer::intValue)
                .summaryStatistics();

        System.out.println("Count: " + stats.getCount());
        System.out.println("Sum: " + stats.getSum());
        System.out.println("Min: " + stats.getMin());
        System.out.println("Max: " + stats.getMax());
        System.out.println("Average: " + stats.getAverage());

        System.out.println("------------------------------");

        stats = numbers.stream()
                .collect(Collectors.summarizingInt(Integer::intValue));

        System.out.println("Count: " + stats.getCount());
        System.out.println("Sum: " + stats.getSum());
        System.out.println("Min: " + stats.getMin());
        System.out.println("Max: " + stats.getMax());
        System.out.println("Average: " + stats.getAverage());
        System.out.println("------------------------------");
    }
}

Output 
------------------------------------
Count: 5
Sum: 150
Min: 10
Max: 50
Average: 30.0
------------------------------------
Count: 5
Sum: 150
Min: 10
Max: 50
Average: 30.0
------------------------------------