Java By Comparison

Favor Method References Over Lambdas

class Inventory {

    List<Supply> supplies = new ArrayList<>();

    long countDifferentKinds() {
        return supplies.stream()
                       .filter(supply -> !supply.isContaminated())
                       .map(supply -> supply.getName())
                       .distinct()
                       .count();
    }
}

Lambda expressions like you’ve seen them in the previous comparison can make your code more readable. But these benefits come at a price: you can’t execute lambda expressions partway—you can only run the whole stream. That means it’s hard to test parts of lambda expressions as you’d want to do in a unit test.

Above, you can see a slightly modified solution from the previous comparison: ​Favor Functional Over Imperative Style​ that uses a logical negation. It contains ...