Where is my code?

2015-11-27

A lib I’ve used often lately is Project Lombok. Lombok fills the gap between Java and some C# syntactic sugar features that makes me slightly jealous ;).

Getter and Setter

Something I liked back in my C# days was the syntax of simple getter and setter without any logic:

public class Person
{
    public string Firstname { get; set; }
    public string Lastname { get; set; }
}

Neat and clean compared to the Java version:

public class Person {
    String firstname;
    String lastname;

    public String getFirstname() {
        return firstname;
    }

    public void setFirstname(String firstname) {
        this.firstname = firstname;
    }

    public String getLastname() {
        return lastname;
    }

    public void setLastname(String lastname) {
        this.lastname = lastname;
    }
}

Lombok helps out this annoyance:

public class Person {
    @Getter
    @Setter
    public String firstname;
    @Getter
    @Setter
    public String lastname;
}

Just as nice as in C#, isn’t it?

@Data

Although I have not used it yet, the saving of boilerplate code when using the @Data annotation is impressive.



@Data
public class DataExample {
    private final String name;
    @Setter(AccessLevel.PACKAGE)
    private int age;
    private double score;
    private String[] tags;

    @ToString(includeFieldNames = true)
    @Data(staticConstructor = "of")
    public static class Exercise<T> {
        private final String name;
        private final T value;
    }
}

Is the same as

public class DataExample {
    private final String name;
    private int age;
    private double score;
    private String[] tags;

    public DataExample(String name) {
        this.name = name;
    }

    public String getName() {
        return this.name;
    }

    void setAge(int age) {
        this.age = age;
    }

    public int getAge() {
        return this.age;
    }

    public void setScore(double score) {
        this.score = score;
    }

    public double getScore() {
        return this.score;
    }

    public String[] getTags() {
        return this.tags;
    }

    public void setTags(String[] tags) {
        this.tags = tags;
    }

    @Override
    public String toString() {
        return "DataExample(" + this.getName() + ", " + this.getAge() + ", " + this.getScore() + ", " + Arrays.deepToString(this.getTags()) + ")";
    }

    protected boolean canEqual(Object other) {
        return other instanceof DataExample;
    }

    @Override
    public boolean equals(Object o) {
        if (o == this) return true;
        if (!(o instanceof DataExample)) return false;
        DataExample other = (DataExample) o;
        if (!other.canEqual((Object) this)) return false;
        if (this.getName() == null ? other.getName() != null : !this.getName().equals(other.getName())) return false;
        if (this.getAge() != other.getAge()) return false;
        if (Double.compare(this.getScore(), other.getScore()) != 0) return false;
        if (!Arrays.deepEquals(this.getTags(), other.getTags())) return false;
        return true;
    }

    @Override
    public int hashCode() {
        final int PRIME = 59;
        int result = 1;
        final long temp1 = Double.doubleToLongBits(this.getScore());
        result = (result * PRIME) + (this.getName() == null ? 43 : this.getName().hashCode());
        result = (result * PRIME) + this.getAge();
        result = (result * PRIME) + (int) (temp1 ^ (temp1 >>> 32));
        result = (result * PRIME) + Arrays.deepHashCode(this.getTags());
        return result;
    }

    public static class Exercise<T> {
        private final String name;
        private final T value;

        private Exercise(String name, T value) {
            this.name = name;
            this.value = value;
        }

        public static <T> Exercise<T> of(String name, T value) {
            return new Exercise<T>(name, value);
        }

        public String getName() {
            return this.name;
        }

        public T getValue() {
            return this.value;
        }

        @Override
        public String toString() {
            return "Exercise(name=" + this.getName() + ", value=" + this.getValue() + ")";
        }

        protected boolean canEqual(Object other) {
            return other instanceof Exercise;
        }

        @Override
        public boolean equals(Object o) {
            if (o == this) return true;
            if (!(o instanceof Exercise)) return false;
            Exercise<?> other = (Exercise<?>) o;
            if (!other.canEqual((Object) this)) return false;
            if (this.getName() == null ? other.getValue() != null : !this.getName().equals(other.getName()))
                return false;
            if (this.getValue() == null ? other.getValue() != null : !this.getValue().equals(other.getValue()))
                return false;
            return true;
        }

        @Override
        public int hashCode() {
            final int PRIME = 59;
            int result = 1;
            result = (result * PRIME) + (this.getName() == null ? 43 : this.getName().hashCode());
            result = (result * PRIME) + (this.getValue() == null ? 43 : this.getValue().hashCode());
            return result;
        }
    }
}

One disadvantage I’ve noticed was refactoring support although there is a Lombok plugin for Eclipse and IntelliJ

For classes annotated with @Data Lombok will generate the getters and setters based on the field names. If you use one of those getters in another class and then rename it, there is no refactoring of those getters and setters.

There are some other nice feature like implicit typed variables with valand imutable classes with @Value. I think it’s worth a look.