Java8 find the sum of even numbers square using lambda expression

Below are the code to get sum of even numbers square using lambda expression.

public static void main(String[] args) {
		 List<Integer> listInt = Arrays.asList(1, 2, 3, 4, 5);
		 IntSummaryStatistics summaryStatistics= listInt.stream().
		 filter((i)->i%2==0 ).mapToInt((i)->+i*i).summaryStatistics();
		 System.out.println(summaryStatistics.getSum());
	}

In line 2 we have created a list of integer and assign it to a variable called listInt.

In line 3 we created a return type IntSummaryStatistics

On the right side we created a stream listInt.stream() of that list .

In line 3 we applied a filter which is filtering only even numbers filter((i)->i%2==0 ). 

Filter() accepts predicate as a argument , predicate interface given below to check the condition and return boolean response. Its a functional interface  has a method called test which takes a parameter and return boolean response.

@FunctionalInterface
public interface Predicate<T> {
  boolean test(T t);
}

after that we mapped the result in Int type and while mapping the result we square all the even numbers mapToInt((i)->+i*i). At last we called the summary statistics and collect the entire data   summaryStatistics();

In line 4 we used the collected data and get the sum of all values. 

Find more about streams basics in the link.