How to groupBy object properties and map to another object using Java 8 Streams?

Question

Suppose I have a group of bumper cars, which have a size, a color and an identifier (\"car code\") on their sides.

class BumperCar {
    int size;
    String col         


        

Answer 1

Check out my library AbacusUtil:

StreamEx.of(bumperCars)
         .groupBy(c -> Tuple.of(c.getSize(), c.getColor()), BumperCar::getCarCode)
         .map(e -> new DistGroup(e.getKey()._1, e.getKey()._2, e.getValue())
         .toList();