The Collectors.counting retuns a Collector that counts the number of elements in the stream.
Java 8 Stream Collectors.counting() exmaple
The example counts the number of elements in the list:
import java.util.List;
import java.util.ArrayList;
import java.util.stream.Collectors;
public class JavaCollectToListEx {
public static void main(String[] args) {
List < String > programmingLanguages = new ArrayList < > ();
programmingLanguages.add("C");
programmingLanguages.add("C++");
programmingLanguages.add("Java");
programmingLanguages.add("Kotlin");
programmingLanguages.add("Python");
programmingLanguages.add("Perl");
programmingLanguages.add("Ruby");
// filter all four character words into a list
long result = programmingLanguages.stream().collect(Collectors.counting());
System.out.println(result);
}
}
Output:
7