package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

package com.example.demo;

import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

@Component
public class ExampleBean {

    public ExampleBean() {
        System.out.println("Constructor: ExampleBean is created");
    }

    @PostConstruct
    public void init() {
        System.out.println("PostConstruct: ExampleBean is initialized");
    }

    @PreDestroy
    public void cleanup() {
        System.out.println("PreDestroy: ExampleBean is about to be destroyed");
    }
}

Constructor: ExampleBean is created
PostConstruct: ExampleBean is initialized

PreDestroy: ExampleBean is about to be destroyed