Starting from 4.2, Spring annotations can be processed when used on Java 8 default methods as well. This allows for a lot of flexibility in creating complex bean implementations and configuration classes (the class with @Configuration). We can even take the advantage of Java 8 default method's multiple inheritance behavior pattern.

Let's see how to use Spring annotations on Java 8 default methods.

Example

An interface for bean

package com.logicbig.example;

import jakarta.annotation.PostConstruct;

public interface IMyBean {
  @PostConstruct
  default void init() {
      System.out.println("post construct: "+this.getClass().getSimpleName());
  }
}

The implementation

package com.logicbig.example;

public class MyBean implements IMyBean {

  public void showMessage(String msg) {
      System.out.println(msg);
  }
}

An interface for configuration

package com.logicbig.example;

import org.springframework.context.annotation.Bean;

public interface IMyConfig {
  @Bean
  default MyBean myBean() {
      return new MyBean();
  }
}

The implementation

package com.logicbig.example;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Configuration;

@Configuration
public class MyConfig implements IMyConfig {
  public static void main(String[] args) {
      ApplicationContext context =
              new AnnotationConfigApplicationContext(MyConfig.class);
      MyBean bean = context.getBean(MyBean.class);
      bean.showMessage("a test message");
  }
}

Output

post construct: MyBean
a test message

Example Project

Dependencies and Technologies Used:

• spring-context 6.1.2 (Spring Context)
   Version Compatibility: 4.2.0.RELEASE - 6.1.2Version List
  ×

  Version compatibilities of spring-context with this example:

  • 4.2.0.RELEASE
  • 4.2.1.RELEASE
  • 4.2.2.RELEASE
  • 4.2.3.RELEASE
  • 4.2.4.RELEASE
  • 4.2.5.RELEASE
  • 4.2.6.RELEASE
  • 4.2.7.RELEASE
  • 4.2.8.RELEASE
  • 4.2.9.RELEASE
  • 4.3.0.RELEASE
  • 4.3.1.RELEASE
  • 4.3.2.RELEASE
  • 4.3.3.RELEASE
  • 4.3.4.RELEASE
  • 4.3.5.RELEASE
  • 4.3.6.RELEASE
  • 4.3.7.RELEASE
  • 4.3.8.RELEASE
  • 4.3.9.RELEASE
  • 4.3.10.RELEASE
  • 4.3.11.RELEASE
  • 4.3.12.RELEASE
  • 4.3.13.RELEASE
  • 4.3.14.RELEASE
  • 4.3.15.RELEASE
  • 4.3.16.RELEASE
  • 4.3.17.RELEASE
  • 4.3.18.RELEASE
  • 4.3.19.RELEASE
  • 4.3.20.RELEASE
  • 4.3.21.RELEASE
  • 4.3.22.RELEASE
  • 4.3.23.RELEASE
  • 4.3.24.RELEASE
  • 4.3.25.RELEASE
  • 4.3.26.RELEASE
  • 4.3.27.RELEASE
  • 4.3.28.RELEASE
  • 4.3.29.RELEASE
  • 4.3.30.RELEASE
  • 5.0.0.RELEASE
  • 5.0.1.RELEASE
  • 5.0.2.RELEASE
  • 5.0.3.RELEASE
  • 5.0.4.RELEASE
  • 5.0.5.RELEASE
  • 5.0.6.RELEASE
  • 5.0.7.RELEASE
  • 5.0.8.RELEASE
  • 5.0.9.RELEASE
  • 5.0.10.RELEASE
  • 5.0.11.RELEASE
  • 5.0.12.RELEASE
  • 5.0.13.RELEASE
  • 5.0.14.RELEASE
  • 5.0.15.RELEASE
  • 5.0.16.RELEASE
  • 5.0.17.RELEASE
  • 5.0.18.RELEASE
  • 5.0.19.RELEASE
  • 5.0.20.RELEASE
  • 5.1.0.RELEASE
  • 5.1.1.RELEASE
  • 5.1.2.RELEASE
  • 5.1.3.RELEASE
  • 5.1.4.RELEASE
  • 5.1.5.RELEASE
  • 5.1.6.RELEASE
  • 5.1.7.RELEASE
  • 5.1.8.RELEASE
  • 5.1.9.RELEASE
  • 5.1.10.RELEASE
  • 5.1.11.RELEASE
  • 5.1.12.RELEASE
  • 5.1.13.RELEASE
  • 5.1.14.RELEASE
  • 5.1.15.RELEASE
  • 5.1.16.RELEASE
  • 5.1.17.RELEASE
  • 5.1.18.RELEASE
  • 5.1.19.RELEASE
  • 5.1.20.RELEASE
  • 5.2.0.RELEASE
  • 5.2.1.RELEASE
  • 5.2.2.RELEASE
  • 5.2.3.RELEASE
  • 5.2.4.RELEASE
  • 5.2.5.RELEASE
  • 5.2.6.RELEASE
  • 5.2.7.RELEASE
  • 5.2.8.RELEASE
  • 5.2.9.RELEASE
  • 5.2.10.RELEASE
  • 5.2.11.RELEASE
  • 5.2.12.RELEASE
  • 5.2.13.RELEASE
  • 5.2.14.RELEASE
  • 5.2.15.RELEASE
  • 5.2.16.RELEASE
  • 5.2.17.RELEASE
  • 5.2.18.RELEASE
  • 5.2.19.RELEASE
  • 5.2.20.RELEASE
  • 5.2.21.RELEASE
  • 5.2.22.RELEASE
  • 5.2.23.RELEASE
  • 5.2.24.RELEASE
  • 5.2.25.RELEASE
  • 5.3.0
  • 5.3.1
  • 5.3.2
  • 5.3.3
  • 5.3.4
  • 5.3.5
  • 5.3.6
  • 5.3.7
  • 5.3.8
  • 5.3.9
  • 5.3.10
  • 5.3.11
  • 5.3.12
  • 5.3.13
  • 5.3.14
  • 5.3.15
  • 5.3.16
  • 5.3.17
  • 5.3.18
  • 5.3.19
  • 5.3.20
  • 5.3.21
  • 5.3.22
  • 5.3.23
  • 5.3.24
  • 5.3.25
  • 5.3.26
  • 5.3.27
  • 5.3.28
  • 5.3.29
  • 5.3.30
  • 5.3.31
  Compatible Java Version: 17+
  • 6.0.0
  • 6.0.1
  • 6.0.2
  • 6.0.3
  • 6.0.4
  • 6.0.5
  • 6.0.6
  • 6.0.7
  • 6.0.8
  • 6.0.9
  • 6.0.10
  • 6.0.11
  • 6.0.12
  • 6.0.13
  • 6.0.14
  • 6.0.15
  • 6.1.0
  • 6.1.1
  • 6.1.2

  Versions in green have been tested.

• jakarta.jakartaee-api 10.0.0 (Eclipse Foundation)
  
• JDK 17
• Maven 3.8.1