Java By Comparison

Favor Lambdas Over Anonymous Classes

class Calculator {

    Map<Double, Double> values = new HashMap<>();

    Double square(Double x) {
        Function<Double, Double> squareFunction =
                new Function<Double, Double>() {
                    @Override
                    public Double apply(Double value) {
                        return value * value;
                    }
                };
        return values.computeIfAbsent(x, squareFunction);
    }
}

In Java 8, several existing classes (such as Map) got a boost with more useful methods. In the code above, you can see one of them named computeIfAbsent(). This method gets a value from the map using its key, and if the key isn’t already present in the map, it computes the value first. Pretty neat. We’ve written similar code many times by hand before.

But to use that new method, ...