Question

I need some code samples (and I also really curious about them) of Scala and Java code which show that Scala code is more simple and concise then code written in Java (of course both samples should solve the same problem).

If there is only Scala sample with comment like “this is abstract factory in Scala, in Java it will look much more cumbersome” then this is also acceptable.

Thanks!

I like most of all accepted and this answers

Answer 1

Let’s improve stacker’s example and use Scala’s case classes:

case class Person(firstName: String, lastName: String)

The above Scala class contains all features of the below Java class, and some more – for example it supports pattern matching (which Java doesn’t have). Scala 2.8 adds named and default arguments, which are used to generate a copy method for case classes, which gives the same ability as the with* methods of the following Java class.

public class Person implements Serializable {
    private final String firstName;
    private final String lastName;

    public Person(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public Person withFirstName(String firstName) {
        return new Person(firstName, lastName);
    }

    public Person withLastName(String lastName) {
        return new Person(firstName, lastName);
    }

    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        Person person = (Person) o;
        if (firstName != null ? !firstName.equals(person.firstName) : person.firstName != null) {
            return false;
        }
        if (lastName != null ? !lastName.equals(person.lastName) : person.lastName != null) {
            return false;
        }
        return true;
    }

    public int hashCode() {
        int result = firstName != null ? firstName.hashCode() : 0;
        result = 31 * result + (lastName != null ? lastName.hashCode() : 0);
        return result;
    }

    public String toString() {
        return "Person(" + firstName + "," + lastName + ")";
    }
}

Then, in usage we have (of course):

Person mr = new Person("Bob", "Dobbelina");
Person miss = new Person("Roberta", "MacSweeney");
Person mrs = miss.withLastName(mr.getLastName());

Against

val mr = Person("Bob", "Dobbelina")
val miss = Person("Roberta", "MacSweeney")
val mrs = miss copy (lastName = mr.lastName)