This method returns the count of elements in this stream. This is a special case of a reduction and is equivalent to:
This is a terminal operation.
Using Stream#count method and comparing with equivalent reduce operation.
package com.logicbig.example;
import java.util.stream.Stream;
public class CountExample {
public static void main (String[] args) {
runCount();
runEquivalentReduce();
runEquivalentSum();
}
private static void runCount () {
long c = Stream.of("banana", "pie", "apple").count();
System.out.println(c);
}
private static void runEquivalentReduce () {
long sum = Stream.of("banana", "pie", "apple")
.mapToLong(s -> 1L)
.reduce(0, Long::sum);
System.out.println(sum);
}
private static void runEquivalentSum () {
long sum = Stream.of("banana", "pie", "apple")
.mapToLong(s -> 1L).sum();
System.out.println(sum);
}
}
Output
3
3
3
Original Post