Add an implementation, such as Hibernate Validator, to the classpath error using springboot

Question

I m new to Spring Boot and built my first simple project but have a problem when running the application.

Could you please tell me why it s giving an error , below?

pom.xml

    <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>
  <groupId>io.javabrains.springbootquickstart</groupId>
  <artifactId>course-api</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>java Brains Course API</name>
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.1.RELEASE</version>
  </parent>
  <dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
     </dependency>
     <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
        </dependency>
  </dependencies>
  <properties>
    <java.version>1.8</java.version>
  </properties>
</project> 

CourseApiApp.java

    package io.javabrains.springbootstarter;

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

@SpringBootApplication
public class CourseApiApp {

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

    }

}

This screenshot belongs my example.

Console output below: Application failed to start. "Add an implementation, such as Hibernate Validator, to the classpath"

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.1.RELEASE)

2018-01-09 11:31:47.216  INFO 12224 --- [           main] i.j.springbootstarter.CourseApiApp       : Starting CourseApiApp on kafein-kafein with PID 12224 (C:\Users\kafein\Documents\workspace-sts-3.9.2.RELEASE\course-api\target\classes started by kafein in C:\Users\kafein\Documents\workspace-sts-3.9.2.RELEASE\course-api)
2018-01-09 11:31:47.223  INFO 12224 --- [           main] i.j.springbootstarter.CourseApiApp       : No active profile set, falling back to default profiles: default
2018-01-09 11:31:47.314  INFO 12224 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@2a8448fa: startup date [Tue Jan 09 11:31:47 EET 2018]; root of context hierarchy
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.springframework.cglib.core.ReflectUtils$1 (file:/C:/Users/kafein/.m2/repository/org/springframework/spring-core/4.3.6.RELEASE/spring-core-4.3.6.RELEASE.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
WARNING: Please consider reporting this to the maintainers of org.springframework.cglib.core.ReflectUtils$1
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
2018-01-09 11:31:48.148  WARN 12224 --- [           main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'standardJacksonObjectMapperBuilderCustomizer' defined in class path resource [org/springframework/boot/autoconfigure/jackson/JacksonAutoConfiguration$Jackson2ObjectMapperBuilderCustomizerConfiguration.class]: Unsatisfied dependency expressed through method 'standardJacksonObjectMapperBuilderCustomizer' parameter 1; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'spring.jackson-org.springframework.boot.autoconfigure.jackson.JacksonProperties': Initialization of bean failed; nested exception is javax.validation.ValidationException: Unable to create a Configuration, because no Bean Validation provider could be found. Add a provider like Hibernate Validator (RI) to your classpath.
2018-01-09 11:31:48.156  INFO 12224 --- [           main] utoConfigurationReportLoggingInitializer : 

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2018-01-09 11:31:48.162 ERROR 12224 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

The Bean Validation API is on the classpath but no implementation could be found

Action:

Add an implementation, such as Hibernate Validator, to the classpath

Solution 1

You are missing some libs. Add the following Spring Boot dependency to your pom.xml to solve it. Spring Boot will find out the correct implementations to use in your project.

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

Also, add Hibernate Dependencies:

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- Hibernate -->
<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-ehcache</artifactId>
  <exclusions>
    <exclusion>
      <groupId>net.sf.ehcache</groupId>
      <artifactId>ehcache</artifactId>
    </exclusion>
  </exclusions>
</dependency>
<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-java8</artifactId>
</dependency>

Solution 2

There should be fixed in the latest spring boot versions per this link: https://github.com/spring-projects/spring-boot/pull/12669 (Allow validation api in the classpath without an implementation). In case of older boot versions, another option to fix this exception is to exclude the vaidation API. Example below when using spring-boot-starter web:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>        
        <exclusion>
            <groupId>javax.validation</groupId>
            <artifactId>validation-api</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Solution 3

I only needed to add:

compile 'org.springframework.boot:spring-boot-starter-validation'