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Ted’s Tool TimeTed VinkeFirst8
Code Generation with Groovy,
Lombok, AutoValue and Immutables
July 2016
Reducing boilerplate
Project Lombok
https://projectlombok.org/
@NonNull
@Cleanup
@Getter / @Setter
@ToString
@EqualsAndHashCode
@NoArgsConstructor,
@RequiredArgsConstructor and
@AllArgsConstructor
@Data
Project Lombok
import lombok.AllArgsConstructor; import lombok.EqualsAndHashCode; import lombok.ToString;
@ToString @AllArgsConstructor @EqualsAndHashCode public class Person {
private String lastName;private String firstName;
}
Value objects
Immutability in plain old Java
● final
● final private
● construction in a single step
● defensive copying
● no mutators
● ...
public final class Planet {
private final double mass; private final String name;private final Date dateOfDiscovery;
public Planet (double mass, String mame, Date dateOfDiscovery) {this.mass = mass;this.name = name;this.dateOfDiscovery = new Date(dateOfDiscovery.getTime());
}
public double getMass() {return mass;
}
public String getName() {return name;
}
public Date getDateOfDiscovery() {return new Date(dateOfDiscovery.getTime());
}
}
Equals, hashCode in plain-old Java
public final class Location {private final String countryCode;private final int priority;
public Location(String countryCode, int priority) {this.countryCode = countryCode;this.priority = priority;
}
@Overridepublic int hashCode() {
final int prime = 31;int result = 1;result = prime * result + ((countryCode == null) ? 0 :
countryCode.hashCode());result = prime * result + priority;return result;
}
@Overridepublic boolean equals(Object obj) {
if (this == obj)return true;
if (obj == null)return false;
if (!(obj instanceof Location))return false;
Location other = (Location) obj;if (countryCode == null) {
if (other.countryCode != null)return false;
} else if (!countryCode.equals(other.countryCode))return false;
if (priority != other.priority)return false;
return true;}
}
@Value
Project Lombok
import lombok.experimental.Value;
@Value public class Location {
String countryCode;int priority;
}
And...
Dates, Cloneables and arrays are
defensively copied on the way
in (constructor) and out
(getters).
Collections and Maps are wrapped
by immutable wrapper classes.
@Immutable
import groovy.transform.Immutable
@Immutableclass Location {
String countryCodeint priority
}
AutoValue
https://github.com/google/auto/tree/
master/value
Generated immutable value classes for
Java 1.6+
@AutoValue
Google AutoValue
import com.google.auto.value.AutoValue;
@AutoValue abstract class Location {
static Location create(String countryCode, int priority) {return new AutoValue_Location(countryCode, priority)
}
abstract String countryCode()abstract int priority()
}
Generated
AutoValue_Location.java
import javax.annotation.Generated;
@Generated("com.google.auto.value.processor.AutoValueProcessor") final class AutoValue_Location extends Location {
private final String countryCode; private final int priority;
AutoValue_Location( String countryCode, int priority) {
if (countryCode == null) { throw new NullPointerException("Null countryCode");
} ...
}
@Override String countryCode() {
return countryCode; }
@Value.Immutable
import org.immutables.value.Value;
@Value.Immutable abstract class Location {
abstract String countryCode()abstract int priority()
}
Generated
ImmutableLocation.java
import javax.annotation.Generated;
@SuppressWarnings("all") @Generated({"Immutables.generator", "Location"}) final class ImmutableLocation extends Location {
private final String countryCode; private final int priority;
private ImmutableLocation(String countryCode, int priority) {
this.countryCode = countryCode; this.priority = priority;
}
@Override String countryCode() {
return countryCode; }
public static ImmutablePerson.Builder builder() { return new ImmutablePerson.Builder();
}
Annotation processing
Lombok, AutoValue, and Immutables all employ annotation processing via
javac, Groovy uses groovyc
AutoValue and Immutables generate new source - which extend template class
e.g. Location.java -> AutoValue_Location.java extends Location
Groovy and Lombok modify the AST and enhances compiled class
That's it!
Project Lombok - https://projectlombok.org/
Groovy - http://www.groovy-lang.org/
AutoValue - https://github.com/google/auto/blob/master/value
Immutables - http://immutables.github.io/
http://culttt.com/2014/04/30/difference-entities-value-objects/
http://marxsoftware.blogspot.nl/2016/06/lombok-autovalue-immutables.htmlThank you
