In my project, I am using lombok to avoid writing getters and setters for a class. Also, I am using lombok.Builder to build an object instead of writing new Obeject() and then setting all the values.
But when we have inheritance relationship and when we want to construct child object using lombok builder, I am not getting parent's field.
For example:
@Data
@NoArgsConstructor
@AllArgsConstructor
@ToString
@EqualsAndHashCode
public class Parent{
private String nationality;
.
.
// more columns
}
And Child class would be something like this:
@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public class Child extends Parent{
private String firstName;
private String lastName;
.
.
}
In my test class, where I need to build child object
public class Test{
public void testMethod(){
Child child = Child.builder()
.firstName("Rakesh")
.lastName("SS")
.nationality("some text")// I am not able to set nationality
.build();
}
}
Please let me know, is there any way to handle this scenario in lombok.
@Builder
has no way to determine which fields of Parent
you wish to expose.
When @Builder
is placed on a class, only fields explicitly declared on that class are added to the *Builder
.
When @Builder
is placed on a static method or a constructor the resulting *Builder
will have a method for each argument.
Also if you are using @Builder
then is it safe to assume that at least Child
is meant to be immutable?
I supply two examples, one where Parent
is mutable and Child
is immutable and one where both Parent
and Child
are immutable.
import static org.junit.Assert.*;
import lombok.Builder;
import lombok.EqualsAndHashCode;
import lombok.ToString;
import lombok.Value;
import lombok.experimental.NonFinal;
import org.junit.Test;
public class So32989562ValueTest {
@Value
@NonFinal
public static class Parent {
protected final String nationality;
}
@Value
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public static class Child extends Parent {
private final String firstName;
private final String lastName;
@Builder(toBuilder = true)
private Child(String nationality, String firstName, String lastName) {
super(nationality);
this.firstName = firstName;
this.lastName = lastName;
}
}
@Test
public void testChildBuilder() {
String expectedFirstName = "Jeff";
String expectedLastName = "Maxwell";
String expectedNationality = "USA";
Child result = Child.builder()
.firstName(expectedFirstName)
.lastName(expectedLastName)
.nationality(expectedNationality)
.build();
assertEquals(result.toString(), expectedFirstName, result.getFirstName());
assertEquals(result.toString(), expectedLastName, result.getLastName());
assertEquals(result.toString(), expectedNationality, result.getNationality());
}
}
import static org.junit.Assert.*;
import lombok.Builder;
import lombok.Data;
import lombok.EqualsAndHashCode;
import lombok.ToString;
import lombok.Value;
import org.junit.Test;
public class So32989562DataTest {
@Data
public static class Parent {
protected String nationality;
}
@Value
@ToString(callSuper = true)
@EqualsAndHashCode(callSuper = true)
public static class Child extends Parent {
private final String firstName;
private final String lastName;
@Builder(toBuilder = true)
private Child(String nationality, String firstName, String lastName) {
this.setNationality(nationality);
this.firstName = firstName;
this.lastName = lastName;
}
}
@Test
public void testChildBuilder() {
String expectedFirstName = "Jeff";
String expectedLastName = "Maxwell";
String expectedNationality = "USA";
Child result = Child.builder()
.firstName(expectedFirstName)
.lastName(expectedLastName)
.nationality(expectedNationality)
.build();
assertEquals(result.toString(), expectedFirstName, result.getFirstName());
assertEquals(result.toString(), expectedLastName, result.getLastName());
assertEquals(result.toString(), expectedNationality, result.getNationality());
}
}
Above solution works, however that requires too much workaround. And further any changes in child and parent class requires changing constructor arguments everywhere.
Lombok has introduced experimental features with version: 1.18.2 for inheritance issues faced with Builder annotation, and can be resolved with @SuperBuilder annotation as below.
@SuperBuilder
public class ParentClass {
private final String a;
private final String b;
}
@SuperBuilder
public class ChildClass extends ParentClass{
private final String c;
}
Now, one can use Builder class as below (that was not possible with @Builder annotation)
ChildClass.builder().a("testA").b("testB").c("testC").build();
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