Stream2.java

Map<String, List<Thing>> consumerDevicesByAge =
        consumerList
                .stream()
                // filter is an intermediate operation
                .filter(consumer -> consumer.getAge() > 30)
                // collect is a terminal operation
                .collect(Collectors.toMap(Consumer::getName, Consumer::getThings));

// In the above code, used 'Method reference(shorthand form of lamda)' Consumer::getName which is equalent to consumer -> consumer.getName()
System.out.println(consumerDevicesByAge);
// Output: {Bob=[Thing(name=Bulb), Thing(name=MotionDetector), Thing(name=AgriFieldSensor), Thing(name=EyeVirusDetector)], Sri=[Thing(name=Bulb), Thing(name=EyeVirusDetector)]}