Apart from the for(:) loop at (2) to iterate over all elements of the list and read the number of…
Parallel Mutable Reduction Figure 16.14 shows the stream pipeline from Figure 16.13, where the sequential stream (2a) has been replaced…
Collecting to a Set The method toSet() creates a collector that uses a mutable container of type Set to perform…
Averaging Another common statistics to calculate is the average of values, defined as the sum of values divided by the…
Collecting to a ConcurrentMap If the collector returned by the Collectors.toMap() method is used in a parallel stream, the multiple…
Grouping Classifying elements into groups based on some criteria is a very common operation. An example is classifying CDs into…
16.8 Collectors A collector encapsulates the functions required for performing reduction: the supplier, the accumulator, the combiner, and the finisher.…
Multilevel Grouping The downstream collector in a groupingBy() operation can be created by another groupingBy() operation, resulting in a multilevel…
Grouping to a ConcurrentMap If the collector returned by the Collectors.groupingBy() method is used in a parallel stream, the partial…