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Application Runner and Command Line Runner interfaces lets you to execute the code after the Spring Boot application is started.

You can use these interfaces to perform any actions immediately after the application has started.

Application Runner

package com.codeFactory;import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootFileUploadApplication implements ApplicationRunner {
public static void main(String[] args) {
SpringApplication.run(SpringBootFileUploadApplication.class, args);
}
@Override
public void run(ApplicationArguments args) throws Exception {
System.out.println("ApplicationRunner");
}
}

Command Line Runner

package com.codeFactory;import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootFileUploadApplication implements CommandLineRunner {
public static void main(String[] args) {
SpringApplication.run(SpringBootFileUploadApplication.class, args);
}
@Override
public void run(String... args) throws Exception {
System.out.println("CommandLineRunner");
}
}