To use Log4j2, we need to use the starter spring-boot-starter-log4j2. When we use starters such as spring-boot-starter-web, we need to ensure that we exclude the dependency in spring-boot-starter-logging. The following snippet shows the details:

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
      <exclusions>
        <exclusion>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-logging</artifactId>
        </exclusion>
       </exclusions>
    </dependency>

    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-log4j2</artifactId>
    </dependency>

The following snippet shows the dependencies used in the spring-boot-starter-log4j2 starter:

    <dependency>
      <groupId>org.apache.logging.log4j</groupId>
      <artifactId>log4j-slf4j-impl</artifactId>
    </dependency>

   <dependency>
     <groupId>org.apache.logging.log4j</groupId>
     <artifactId>log4j-api</artifactId>
   </dependency>

   <dependency>
     <groupId>org.apache.logging.log4j</groupId>
     <artifactId>log4j-core</artifactId>
   </dependency>

  <dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>jul-to-slf4j</artifactId>
  </dependency>