Java 12 introduces a new method to Collectors to perform two different operations on collection and then merge the result. Following is the syntax of teeing method −
Collector<T, ?, R> teeing(
Collector<? super T, ?, R1> downstream1,
Collector<? super T, ?, R2> downstream2,
BiFunction<? super R1, ? super R2, R> merger
)
Here we are performing different functions on a collection and then merge the result using merger BiFunction.
Consider the following program −
Java12Teeing.java
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class Java12Teeing {
public static void main(String[] args) {
// Teeing funcation aggregates the results of two supplied collectors
double mean
= Stream.of(1, 2, 3, 4, 5, 6, 7, 8, 9)
.collect(Collectors.teeing(
Collectors.summingDouble(i -> i), Collectors.counting(),
(sum, n) -> sum / n));
System.out.println("Aggregate value = " + mean);
}
}
Output:
Now run the Java8DateTime as follows −
C:\hitechpoints\workspace\java12-feature\src>java Java12Teeing.java
It should produce the following output −
Aggregate value = 5.0
