Project failed to run after adding spring boot validation dependency-CodePudding

I'm working on a small project. Which uses mongoDB as DB. I want to add validation on my Player bean. But as soon as I add below dependency:

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

In my pom.xml file.

My project starts failing when I run as spring boot app.

Here is my pom.xml:

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.classhacker</groupId>
    <artifactId>tttapi</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>tttapi</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-validation</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Here is my Player bean:

package com.classhacker.tttapi.domain;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;

@Document
public class Player {
    
    @Id
    int _id;
    
    String name;
    
    int gamesWon;

    public Player(int _id, String name, int gamesWon) {
        super();
        this._id = _id;
        this.name = name;
        this.gamesWon = gamesWon;
        }
    
    public int get_id() {
        return _id;
    }
    
    public String getName() {
        return name;
    }
    
    public int getGamesWon() {
        return gamesWon;
    }
    
    @Override
    public String toString() {
        return String.format("Player[id=%d, name=%s, gamesWon=%d]", _id, name, gamesWon);
    }
}

The error I'm getting after adding the validation dependency:

Error: Could not find or load main class com.classhacker.tttapi.DemoApplication
Caused by: java.lang.ClassNotFoundException: com.classhacker.tttapi.DemoApplication

But if I remove spring boot validation dependency my project doesn't give any error.

It will be really helpful if anybody can explain me what is going wrong here.

CodePudding user response：

Have you tried to clean and build the application and then run it? If it did not work then have you tried to "run file" with your @SpringBootApplication annotation?

CodePudding user response：

I understand that you have imported your project from spring initializr and your pom.xml looks same as this spring.io link:-

https://start.spring.io/#!type=maven-project&language=java&platformVersion=2.7.3&packaging=jar&jvmVersion=1.8&groupId=com.example&artifactId=demo&name=demo&description=Demo project for Spring Boot&packageName=com.example.demo&dependencies=data-mongodb,web,devtools,validation

Ideally you should not face ClassNotFoundException. Try:-

reloading all maven dependencies
clean install maven build
restart your IDE
delete local .m2 repository and rebuild

If that doesn't work, try adding following dependency and build project:-

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