Spring Immutable @ConfigurationProperties

There are at least 4 ways of having immutable properties loaded from configuration:

1. A plain Java class

@ConfigurationProperties("acme")
public class AcmeJavaClassProperties {

  private final boolean enabled;
  private final String text;
  private final List<String> list;
  private final float number;

  public AcmeJavaClassProperties(
    boolean enabled,
    String text,
    List<String> list,
    float number
  ) {
    this.enabled = enabled;
    this.text = text;
    this.list = unmodifiableList(list);
    this.number = number;
    }
}

2. A Java record

@ConfigurationProperties("acme")
public record AcmeJavaRecordProperties(
  boolean enabled,
  String text,
  List<String> list,
  float number
) {
}

3. A plain Kotlin class

@ConfigurationProperties("acme")
class AcmeKotlinClassProperties(
  val enabled: Boolean,
  val text: String,
  val list: List<String>,
  val number: Float
)

4. A Kotlin data class

@ConfigurationProperties("acme")
data class AcmeKotlinDataClassProperties (
  val enabled: Boolean,
  val text: String,
  val list: List<String>,
  val number: Float
)

Note that since Spring Boot 3.x @ConstructorBinding annotation is only required to indicate which constructor to use in case there is more than one.

You can also browse older versions:

• Spring Boot 2.x

Test

Review AcmeApplicationTest and ...

./gradlew test