SpringBoot Application error

Below is the Exception comes when you execute : mvn package

Issue: You have more than one class inside the application with 'main" method

solution : Find the other main method and delete or comment that. Or specify the class you need to refer the main method.
Hint : If you create a project using a maven template, most probably it will create a App.java class with main method. So look for that.

You can easily solve by stating the main class. eg: main class is Example.java


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

<configuration>
<mainClass>Example.class</mainClass>
<layout>ZIP</layout>
</configuration>
</plugin>
</plugins>
</build>

for more information refer

https://docs.spring.io/spring-boot/docs/current/maven-plugin/usage.html
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[ERROR] Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.0.3.RELEASE:repackage (default) on project SpringBootTest: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:2.0.3.RELEASE:repackage failed: Unable to find main class -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.springframework.boot:spring-boot-maven-plugin:2.0.3.RELEASE:repackage (default) on project SpringBootTest: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:2.0.3.RELEASE:repackage failed: Unable to find main class
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:225)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
        at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
        at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:319)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
        at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
        at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
        at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
        at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
        at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default of goal org.springframework.boot:spring-boot-maven-plugin:2.0.3.RELEASE:repackage failed: Unable to find main class
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:110)
        at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
        ... 19 more
Caused by: java.lang.IllegalStateException: Unable to find main class
        at org.springframework.boot.loader.tools.Repackager.buildManifest(Repackager.java:300)
        at org.springframework.boot.loader.tools.Repackager.repackage(Repackager.java:238)
        at org.springframework.boot.loader.tools.Repackager.repackage(Repackager.java:195)
        at org.springframework.boot.maven.RepackageMojo.repackage(RepackageMojo.java:220)
        at org.springframework.boot.maven.RepackageMojo.execute(RepackageMojo.java:207)
        at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
        ... 20 more
[ERROR]
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException