[FIXED] Spring boot - Maven - BUILD FAILURE

Issue

Hello I'm having trouble starting spring boot and I really don't know whats going on. I have tried with the POM and the Aplication.properties but I just can't find whats wrong. Here is the log:

---------------------------< com.matt:main >----------------------------
Building main 0.0.1-SNAPSHOT
--------------------------------[ jar ]---------------------------------

--- maven-resources-plugin:3.2.0:resources (default-resources) @ main ---
Using 'UTF-8' encoding to copy filtered resources.
Using 'UTF-8' encoding to copy filtered properties files.
Copying 1 resource
Copying 0 resource

--- maven-compiler-plugin:3.10.1:compile (default-compile) @ main ---
Changes detected - recompiling the module!
Compiling 1 source file to C:\Users\big_i\OneDrive\Escritorio\Matt\Desarrollo\HTML\Porfolio Final\Spring boot\main\target\classes

--- exec-maven-plugin:3.0.0:exec (default-cli) @ main ---
Error: Could not find or load main class ${exec.mainClass}
Caused by: java.lang.ClassNotFoundException: ${exec.mainClass}
Command execution failed.
org.apache.commons.exec.ExecuteException: Process exited with an error: 1 (Exit value: 1)
    at org.apache.commons.exec.DefaultExecutor.executeInternal (DefaultExecutor.java:404)
    at org.apache.commons.exec.DefaultExecutor.execute (DefaultExecutor.java:166)
    at org.codehaus.mojo.exec.ExecMojo.executeCommandLine (ExecMojo.java:982)
    at org.codehaus.mojo.exec.ExecMojo.executeCommandLine (ExecMojo.java:929)
    at org.codehaus.mojo.exec.ExecMojo.execute (ExecMojo.java:457)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:370)
    at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:351)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:171)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:163)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:294)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:960)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:293)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:196)
    at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:104)
    at java.lang.reflect.Method.invoke (Method.java:577)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
    at jdk.internal.reflect.DirectMethodHandleAccessor.invoke (DirectMethodHandleAccessor.java:104)
    at java.lang.reflect.Method.invoke (Method.java:577)
    at org.apache.maven.wrapper.BootstrapMainStarter.start (BootstrapMainStarter.java:47)
    at org.apache.maven.wrapper.WrapperExecutor.execute (WrapperExecutor.java:156)
    at org.apache.maven.wrapper.MavenWrapperMain.main (MavenWrapperMain.java:72)
------------------------------------------------------------------------
BUILD FAILURE
------------------------------------------------------------------------
Total time:  1.861 s
Finished at: 2022-08-01T13:22:03-03:00
------------------------------------------------------------------------
Failed to execute goal org.codehaus.mojo:exec-maven-plugin:3.0.0:exec (default-cli) on project main: Command execution failed.: Process exited with an error: 1 (Exit value: 1) -> [Help 1]

To see the full stack trace of the errors, re-run Maven with the -e switch.
Re-run Maven using the -X switch to enable full debug logging.

For more information about the errors and possible solutions, please read the following articles:
[Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException

---------------------------------------------------------------------- Adding the POM.xml

'''

<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.7.2</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.matt</groupId>
<artifactId>main</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>main</name>
<description>Main handler app</description>
<properties>
    <java.version>17</java.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</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>

''' Right now I'm trying to build with a main.java that just shows something.

package com.matt.handler.Main;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Main {
  @GetMapping("/hola")
    public String test(){
      return("hola Mundo");
    }
}

Solution

If I understand properly, you are missing main class in spring boot:-

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

@SpringBootApplication
public class App {
  public static void main(String[] args) {
            SpringApplication.run(App.class);
        }
 }

You have just implemented @RestController, but to start spring boot application, you need to have main method which will kick start spring boot.

Once you have it, you can then run maven command as below:

mvn clean spring-boot:run

Answered By - Ashish Patil
Answer Checked By - Robin (JavaFixing Admin)