Develop Reference

How do I create an executable jar for my webapp with Maven?

Backgound
I develop a webapp using a REST Interface with Spring. Normally I develop and execute my software with Eclipse. When my program has been started I enter localhost:8080/RESTPath in Chrome to access RESTPath with my program.
Issue
Now I want to build and execute my program with Maven instead with a executeble jar. The issue is that my knowledge with Maven is limited so I'm not sure how to do. Of course I have googled my issue and I have tested some examples but without succes. So far I think I should use the plugin tomcat7-maven-plugin in my POM.xml to generate a jar to execute with java -jar file.jar. I have followed the example with a webapp using tomcat7-maven-plugin but the jar file is never generated: https://www.baeldung.com/executable-jar-with-maven.
My POM:
<?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>2.6.2</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<!-- My project -->
<groupId>tobbe</groupId>
<artifactId>stocks-rest</artifactId>
<packaging>jar</packaging>
<version>1.0.2-SNAPSHOT</version>
<properties>
<java.version>17</java.version>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<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>
<!-- My projects -->
<dependency>
<groupId>tobbe</groupId>
<artifactId>Stocks_Backend</artifactId>
<version>1.0.2-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>tobbe</groupId>
<artifactId>Other</artifactId>
<version>1.0.2-SNAPSHOT</version>
</dependency>
</dependencies>
</project>
Question
how should my POM look like a how should I build with Maven (i.e. mvn clean compile) to create an executable jar?

<?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>2.6.2</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>17</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</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>
You are missing build section in your pom. When you execute mvn clean package you will get the JAR File in the target folder

Class shows up in auto complete but can't be imported -IntelliJ

The Services project uses a class in DataLayer. I have added the dependency to Services POM. When trying to import UserRepository class from DataLayer, IntelliJ autocomplete shows the class but when I press enter,it says "Can not resolve symbol DataLayer".
I checked the local maven repository and can see the Jar file in the proper place.
Tried invalidating cache which did not work.
Reimporting dependencies did not work either.
Here are the POM files of both the projects as well as screenshots from intelliJ
Services - 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.schoolgallery</groupId>
<artifactId>Services</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Services</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</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>
<dependency>
<groupId>com.schoolgallery</groupId>
<artifactId>DataLayer</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
DataLayer - 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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.schoolgallery</groupId>
<artifactId>DataLayer</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>DataLayer</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</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>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
Error appears as :
EDIT
The project has an MVC architecture with separate modules for API,Services and DataLayer.
Please find the project structures for services and datalayer.

Adding the parent POM dependency to the Child projects did the trick !!
<parent>
<artifactId>parent-pom</artifactId>
<groupId>com.schoolgallery</groupId>
<version>0.0.1-SNAPSHOT</version>
</parent>
Remember to change the spring boot starter parent if you have a custom parent POM , because having two parent tags will throw an error.
This is described nicely here

Java spring error persistence imports are not working

I am creating a simple Spring boot project. When I try and use #Entity and #Id etc. I get a cannot resolve error why is this? Have I not installed the correct version of something. My Imports don't seem to be working and are highlighted in red. I am new to spring. I have attachedThe error as an image.
The error is Package javax.persistence does not exist??
My 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>com.JohnSharp</groupId>
<artifactId>Guestbooknew</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Guestbooknew</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.1.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

Right click on your project -> Maven -> Update project.
For intellij:
Right click on your project > Maven > Reimport

SpringApplication.run(HelloWorldExampleApplication.class, args);

the error is in the following line of code-
SpringApplication.run(HelloWorldExampleApplication.class, args);
it says-
Multiple markers at this line
- The type org.springframework.context.ConfigurableApplicationContext cannot be resolved. It is indirectly referenced
from required .class files
- The method run(Class<?>, String...) from the type SpringApplication refers to the missing type
ConfigurableApplicationContext
I've tried running command "mvn dependency:purge-local-repository" and it says mvn not recognised as int/ext command.
i'm using springboot sts plugin in eclipse IDE.
pls. help as i'm a beginner.
pom file
<?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>
<groupId>com.Ideng</groupId>
<artifactId>helloworld</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>HelloWorldExample</name>
<description>hello world example</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</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-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>

i changed the spring version from 2.0.0 to 2.0.1 SNAPSHOT while creating the project from start and it worked

How to package a maven multi-module properly?

I'm building a multi-module rest service with Maven and Spring Boot that will be published on a WebLogic Server, and I'm a bit confuse about how to configure the packaging of the application modules.
My current structure is:
/application
/main (main mehtod for spring-boot)
/api
/service
/dao
The parent project (application folder) is set up as pom packaging, but child projects I'm not sure how to configure it. I believe the correct way would be packaging like .jar file, but i saw some examples on the internet of Java projects with Maven multi-modules defined as war.
can someone tell me what's the correct way to define the child modules packaging in this case?
My parent pom:
<?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>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>pom</packaging>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<javax.inject.version>1</javax.inject.version>
</properties>
<modules>
<module>radarveicular-api</module>
<module>radarveicular-service</module>
<module>radarveicular-main</module>
<module>radarveicular-dao</module>
</modules>
<build>
<plugins>
<plugin>
<artifactId>maven-eclipse-plugin</artifactId>
<configuration>
<downloadSources>true</downloadSources>
<downloadJavadocs>true</downloadJavadocs>
<wtpversion>2.0</wtpversion>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
<encoding>${project.build.sourceEncoding}</encoding>
</configuration>
</plugin>
</plugins>
</build>
</project>
main pom:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-main</artifactId>
<dependencies>
<dependency>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-api</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<!-- Spring Framework -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-tomcat</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-undertow</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
</dependency>
</dependencies>
<build>
<finalName>${project.artifactId}</finalName>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
api pom:
<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>
<parent>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-api</artifactId>
<dependencies>
<dependency>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-service</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
</project>
service pom:
<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>
<parent>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-service</artifactId>
<dependencies>
<dependency>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-dao</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.7.RELEASE</version>
</dependency>
</dependencies>
</project>
dao pom:
<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>
<parent>
<groupId>com.radarveicular</groupId>
<artifactId>radarveicular-application</artifactId>
<version>0.0.1-SNAPSHOT</version>
</parent>
<artifactId>radarveicular-dao</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.3.7.RELEASE</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.4</version>
</dependency>
</dependencies>
</project>

I think your problem is that your parent pom.xml shouldn't handle your spring boot project. Meaning, you should have this in it :
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
I recommend that your pom.xml parent only handles your modules and dependencies as pom packaging :
Packaging
<packaging>pom</packaging>
Modules
<modules>
<module>radarveicular-api</module>
<module>radarveicular-service</module>
<module>radarveicular-main</module>
<module>radarveicular-dao</module>
</modules>
Then, you will have your module radarveicular-main with the spring boot parent :
Parent
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
Packaging
<packaging>war</packaging>
I hope this will help you. =)

I feel your question is more towards designing part of multi module.
Multi module management of application can depend on various things.
One thing could be if you want to deploy each sub module as separate module/service based, which can be turned off/on based on need. In that case it would help you if you build each of module as separate war and deploy them separately.
If you have to deploy it as a single war than most straight forward would to create all dependent modules as jar and include them in parent project. In this way a single war will be deployed.
You can have a hybrid approach of above two.
Hopefully i have understood your question correctly. :)
Happy coding!!