In Java 8, there is predefined counting() method returned by Collectors class counting() method to count the number of elements in a Stream.
Syntax :
public static Collector counting() Where, output is a Collector, acting on a Stream of elements of type T, with its finisher returning the ‘collected’ value of type Long. It is a terminal operation which returns the total count of elements in the stream which reach the collect() method after undergoing various pipelined stream operations such as filtering.
Example 1 : To count the elements in stream of Integers.
// Java code to count number of elements // in stream import java.util.stream.Stream;
import java.util.stream.Collectors;
class counting {
public static void main(String[] args)
{
// creating stream of integers
Stream<Integer> i = Stream.of( 1 , 2 , 3 , 4 , 5 , 6 );
// counting number of integer in stream
long count_int = i.collect(Collectors.counting());
System.out.println(count_int);
}
} |
6
Example 2 : To count the elements in stream of String.
// JAVA code to count number of elements in stream import java.util.stream.Stream;
import java.util.stream.Collectors;
class counting {
public static void main(String[] args)
{
// creating stream of strings
Stream<String> s = Stream.of( "Akash" , "Harsh" ,
"Shubham" , "Nishant" , "Pratik" );
// counting number of strings in stream
long count_string = s.collect(Collectors.counting());
System.out.println(count_string);
}
} |
5