"The type org.springframework.web.WebApplicationInitializer cannot be resolved. It is indirectly referenced from required .class files"

Question

This is the file that contain the error..int the class it says error " The type org.springframework.web.WebApplicationInitializer cannot be resolved. It is indirectly referenced from required .class files - The hierarchy of the type SpringBootWebApplication is inconsistent"

 package java.com;

        import org.springframework.boot.SpringApplication;
        import org.springframework.boot.autoconfigure.SpringBootApplication;
        import org.springframework.boot.builder.SpringApplicationBuilder;
        import org.springframework.boot.context.web.SpringBootServletInitializer;

        @SpringBootApplication
        public class SpringBootWebApplication extends SpringBootServletInitializer {

            @Override
            protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
                return application.sources(SpringBootWebApplication.class);
            }

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

        }

This is the pom.xml code

<?xml version="1.0" encoding="UTF-8"?>
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>spring-boot-web-jsp</artifactId>
    <packaging>war</packaging>
    <name>Spring Boot Web JSP Example</name>
    <description>Spring Boot Web JSP Example</description>
    <version>1.0</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.4.2.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>

        <!-- Web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- Web with Tomcat + Embed -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- JSTL -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

        <!-- Need this to compile JSP -->
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>

        <!-- Need this to compile JSP -->
        <dependency>
            <groupId>org.eclipse.jdt.core.compiler</groupId>
            <artifactId>ecj</artifactId>
            <version>4.6.1</version>
            <scope>provided</scope>
        </dependency>

        <!-- Optional, for bootstrap -->
        <dependency>
            <groupId>org.webjars</groupId>
            <artifactId>bootstrap</artifactId>
            <version>3.3.7</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <!-- Package as an executable jar/war -->
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

Here Spring boot application is extending SpringBootServletInitializer. If I look at SpringBootServletInitializer it implements WebApplicationInitializer. Add below dependency with appropriate version that will resolve SpringBootServletInitializer.

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>5.0.8.RELEASE</version>
</dependency>

Answer 2

It means: "A class that you use needs another class that is not on the classpath." You should make sure to add the required jar to the classpath.

If you are using eclipse, this occurs due to different version of jdk, just changed to the correct, clean and build!