Micronaut: Introspect enums

You can introspect enums by adding the @Introspected annotation to the enum and it can be constructed through the standard valueOf method.

@Introspected
public enum Day {
	SUNDAY(1), MONDAY(2), TUESDAY(3), WEDNESDAY(4), THURSDAY(5), FRIDAY(6), SATURDAY(7);

	private int dayNumber;

	Day(int dayNumber) {
		this.dayNumber = dayNumber;
	}

	public int getDayNumber() {
		return dayNumber;
	}

}

 

Find the below working application.

Step 1: Create new maven project ‘micronaut-introspect-enums’.

Step 2: Update pom.xml with maven dependencies.

pom.xml 

<project xmlns="http://maven.apache.org/POM/4.0.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.sample.app</groupId>
	<artifactId>micronaut-introspect-enums</artifactId>
	<version>1</version>

	<properties>
		<maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
		<micronaut.version>3.7.2</micronaut.version>
		<slf4j.version>2.0.3</slf4j.version>

		<maven.compiler.target>15</maven.compiler.target>
		<maven.compiler.source>15</maven.compiler.source>
	</properties>

	<dependencies>

		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-inject-java</artifactId>
			<version>${micronaut.version}</version>
		</dependency>
		<dependency>
			<groupId>io.micronaut</groupId>
			<artifactId>micronaut-runtime</artifactId>
			<version>${micronaut.version}</version>
		</dependency>


		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-api</artifactId>
			<version>${slf4j.version}</version>
		</dependency>
		<dependency>
			<groupId>org.slf4j</groupId>
			<artifactId>slf4j-simple</artifactId>
			<version>${slf4j.version}</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>

			<plugin>
				<artifactId>maven-assembly-plugin</artifactId>
				<configuration>
					<archive>
						<manifest>
							<mainClass>com.sample.app.App</mainClass>
						</manifest>
					</archive>
					<descriptorRefs>
						<descriptorRef>jar-with-dependencies</descriptorRef>
					</descriptorRefs>
				</configuration>

				<executions>
					<execution>
						<id>make-assembly</id>
						<phase>package</phase>
						<goals>
							<goal>single</goal>
						</goals>
					</execution>
				</executions>
			</plugin>

		</plugins>
	</build>
</project>

 

Step 3: Define Day enum.

 

Day.java

package com.sample.app.model;

import io.micronaut.core.annotation.Introspected;

@Introspected
public enum Day {
	SUNDAY(1), MONDAY(2), TUESDAY(3), WEDNESDAY(4), THURSDAY(5), FRIDAY(6), SATURDAY(7);

	private int dayNumber;

	Day(int dayNumber) {
		this.dayNumber = dayNumber;
	}

	public int getDayNumber() {
		return dayNumber;
	}

}

Step 4: Define main application class.

 

App.java

package com.sample.app;

import com.sample.app.model.Day;

import io.micronaut.context.ApplicationContext;
import io.micronaut.core.beans.BeanIntrospection;

public class App {

	public static void main(String[] args) {
		try (ApplicationContext applicationContext = ApplicationContext.run()) {

			final BeanIntrospection<Day> introspection = BeanIntrospection.getIntrospection(Day.class);
			Day day = introspection.instantiate("WEDNESDAY");

			System.out.println(day + " -> " + day.getDayNumber());

		}

	}
}

Total project structure looks like below.

 

Build the project using mvn package command.

Navigate to the folder where pom.xml is located and execute the command ‘mvn package’.

 

Upon command successful execution, you can see the jar file ‘micronaut-introspect-enums-1-jar-with-dependencies.jar’ in project target folder.

$ls ./target/
archive-tmp
classes
generated-sources
maven-archiver
maven-status
micronaut-introspect-enums-1-jar-with-dependencies.jar
micronaut-introspect-enums-1.jar
test-classes

Execute below command to run the application.

java -jar ./target/micronaut-introspect-enums-1-jar-with-dependencies.jar

$java -jar ./target/micronaut-introspect-enums-1-jar-with-dependencies.jar
WEDNESDAY -> 4

You can download this application from this link.

 

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