In this tutorial, we will see how to get Stream count in Java 8 using Stream count and Collector counting methods.

How to get Stream count:

We can find the number of elements in a stream using two different methods. count() method from Stream class and Collectors.counting() static method from Collectors class.

Syntax:

Syntax- Stream count()
long 	count()
Returns the count of elements in the stream. If no elements are present, the result is 0.
Syntax- Collectors.counting()
public static <T> Collector<T,?,Long> counting()
Returns a Collector accepting elements of type T that counts the number of input elements. If no elements are present, the result is 0.

Get Stream count – count():

Getting the Stream count using Stream’s count() method.

StreamCount.java
import java.util.stream.Stream;

public class StreamCount {
    public static void main(String[] args) {
        Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9);
        System.out.println("Stream Count is: "+stream.count());
    }
}

Output:

Terminal
Stream Count is: 9

Stream count on the filter:

We can also get the count of a stream on applying the filter condition.

StreamCount.java
import java.util.stream.Stream;

public class StreamCount {
    public static void main(String[] args) {
        Stream<Integer> stream = Stream.of(1,2,3,4,5,6,7,8,9);
        Long count = stream.filter(num->(num%2)==0).count();
        System.out.println("There are "+count+" even numbers in the Stream");
    }
}

Output:

Terminal
There are 4 even numbers in the Stream

Get Stream Count – Collectors counting:

Collectors counting is a static method used to calculate the elements in a stream. If there are no elements in a Stream, it returns merely ‘0’ as a result.

StreamCount.java
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class StreamCount {
    public static void main(String[] args) {
        Stream<Integer> stream = Stream.of(1,2,3,4,5,6);
        Long count = stream.collect(Collectors.counting());
        System.out.println("Stream Count: "+count);
    }
}

Output:

Terminal
Stream Count: 6

Done!

Happy Learning 🙂

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