Java Coding Problems

Summing

Let's assume that we want to sum all the weights of melons. We did this in the Sum, max, and min in a stream section via primitive specializations of Stream. Now, let's do it via the summingInt​(ToIntFunction<? super T> mapper) collector:

int sumWeightsGrams = melons.stream()  .collect(Collectors.summingInt(Melon::getWeight));

So, Collectors.summingInt() is a factory method that takes a function that's capable of mapping an object into an int that has to be summed as an argument. A collector is returned that performs the summarization via the collect() method. The following diagram depicts how summingInt() works:

While traversing the ...