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‎README.md

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@@ -8,4 +8,271 @@ If you would like learn about what's new in Spring Framework 5, click [here](htt
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If you'd like to learn more about the cool new reactive types in Spring Framework 5, click [here](https://springframework.guru/spring-web-reactive/)
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You can learn about my Spring Framework 5 Online course [here.](https://courses.springframework.guru/p/spring-framework-5-begginer-to-guru)
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You can learn about my Spring Framework 5 Online course [here.](https://courses.springframework.guru/p/spring-framework-5-begginer-to-guru)
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# Spring Framework 5: Beginner to Guru Course FAQs
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Check out this section for answers to frequently asked questions!
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## Development Environment Setup
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### Recommended Versions
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| Recommended | Reference | Notes |
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| ----------- | --------- | ----- |
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| Oracle Java 8 JDK | [Download](https://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html) | Java 11 is okay, see notes in FAQ |
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| IntelliJ 2018 or Higher | [Download](https://www.jetbrains.com/idea/download/) | Ultimate Edition recommended |
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| Maven 3.6.0 or higher | [Download](https://maven.apache.org/download.cgi) | [Installation Instructions](https://maven.apache.org/install.html)|
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| Gradle 4.8 or higher | [Download](https://gradle.org/install/) | **Note:** Use Version 5 or higher if using Java 11 |
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| Git 2.15 or higher | [Download](https://git-scm.com/downloads) | |
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| Git GUI Clients | [Downloads](https://git-scm.com/downloads/guis) | Not required. But can be helpful if new to Git. SourceTree is a good option for Mac and Windows users. |
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| Spring Boot 2.1 or higher | [What's new](https://content.pivotal.io/springone-platform-2017/whats-new-in-spring-boot-2-0-phillip-webb-madhura-bhave) | |
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### Getting Help With the Course
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#### Udemy Q&A
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Each course section has a Q&A Section. This should always be your first stop. Thousands of people have take this course.
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Check to see if someone else asked a question related to your problem.
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If not, share your problem here. The instructor, teacher's assistants, and other students watch and answer questions.
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#### Slack
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By enrolling in *Spring Framework 5: Beginner to Guru* you can join a Slack community exclusive to this course.
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In Slack you can get help 24 hrs a day, 7 days a week. The instructor, teachers assistants, and other students monitor Slack.
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See section 1 of the course for instructions on how to join.
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#### Do's and Don't of Getting Help
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###### Do - Use Udemy Q&A or Slack
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These resources are monitored by the instructor, teachers assistants, and other students.
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###### Don't - Email or message the instructor directly
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Asking your question in the public forums actually help others learn too. When you go outside the community, this is lost.
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Also, the instructor is not always on-line and does take days off. You are likely to get a much faster response using Udemy Q&A or
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Slack.
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###### Do - Share a Link to your Project on GitHub
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This helps others re-create your problem.
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###### Don't - Share just a short part of the Error
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Example of error shared:
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```xml
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Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.5.3:prepare (default-cli) on project pet-clinic: Maven execution failed, exit code: '1' -> [Help 1]
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```
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In the above example, it is impossible to tell what the root cause is. The person has not shared enough details.
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When seeking help, help others help you!
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###### Do - Share the Error Output in a GitHub Gist Link
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Create a [Gist](https://help.github.com/articles/about-gists/) of the error output to share.
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**Pro-Tip** - You can create a gist from the run window of IntelliJ. In the console, right click > select option for
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create gist.
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###### Don't Share Screenshots
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Using a gist is usually a better option!
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###### Don't - Open GitHub Issues
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Unfortunately, the course has been pirated. Support is for people who are legitimately enrolled in the course. There is
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no way to verify enrollment from GitHub. Thus, problems raised on GitHub will not be addressed.
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**Exception:** One exception is the Pet Clinic project, which is being treated as a community project.
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### Java Version
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#### Which version of Java should I use?
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Majority of the course has been developed on Java 8. The course is being updated to Java 11.
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If you wish to use Java 9 or higher, please modify the following:
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**Note:** If you are on Java 9, or Java 10 you should consider updating to Java 11.
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Update your Maven POM properties to reflect the Java version.
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```xml
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<properties>
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<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
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<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
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<java.version>11</java.version>
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<jaxb.version>2.3.0</jaxb.version>
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<maven.compiler.source>${java.version}</maven.compiler.source>
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<maven.compiler.target>${java.version}</maven.compiler.target>
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</properties>
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```
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The JAXB API is no longer included with Java in Java 9 and higher. You will need to add this dependency as follows:
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```xml
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<dependency>
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<groupId>javax.xml.bind</groupId>
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<artifactId>jaxb-api</artifactId>
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<version>${jaxb.version}</version>
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</dependency>
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<dependency>
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<groupId>com.sun.xml.bind</groupId>
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<artifactId>jaxb-core</artifactId>
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<version>${jaxb.version}</version>
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</dependency>
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<dependency>
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<groupId>com.sun.xml.bind</groupId>
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<artifactId>jaxb-impl</artifactId>
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<version>${jaxb.version}</version>
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</dependency>
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```
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#### Do I need to use the Oracle JDK?
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No. Open JDK should work just as well.
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#### Do I need to pay Oracle for a license to use Java?
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No, the Oracle JDK is free to use for development.
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### Java IDE
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#### Do I meed to use IntelliJ for this course?
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No, all source code examples use Maven or Gradle. Any modern Java IDE supports these build tools.
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#### Is it okay to use Eclipse for this course?
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Yes. However, please understand the instructor has not used Eclipse in over 10 years and will not be able to
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answer IDE related questions.
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#### Can I use the Community Edition of IntelliJ?
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Yes. The Community edition of IntelliJ is very good. The Ultimate Edition does have advanced features to support
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Spring Framework development. These features are used in the course, and will not be available in the
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Community Edition.
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#### How do I get the free 120 Day Trial to IntelliJ Ultimate?
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See section 1 of the course. There is a lecture with a sign-up link to register. You can download IntelliJ Ultimate with a
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free 30 day trial right away. You will be emailed a code with instructions within 3-5 business days. (often faster)
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#### I haven't received my 120 Day Trial code to IntelliJ Ultimate
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If it has been more than 5 days, check your spam folder. (Almost always there!) If not found, email John Thompson. If
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messaging on Udemy please include the email you registered with.
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#### The code I received is not working.
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This is often one of the following:
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* You are entering the code as a license in IntelliJ. It is not a license code. It is a code for JetBrains to
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issue you a 120 day license. Use this [link](https://www.jetbrains.com/store/redeem/) to register with JetBrains.
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* If you get the error ```This coupon code is not applicable to the product.``` often it is because the email you are
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using has been registered with JetBrains in the past. Try using a different email account.
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#### Can I Use the EAP version of IntelliJ?
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Yep! The instructor typically runs on the EAP version to get all the latest features. The EAP version is usually
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very stable. Checkout the latest EAP version [here](https://www.jetbrains.com/idea/whatsnew/)
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## Common Problems
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#### Getting error - Whitelabel Error Page - This application has no explicit mapping for /error...
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This is a generic error page generated by Spring Boot. The root cause can be many different things.
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If you see this web page, you need to view the Spring Boot console messages to determine the root cause.
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#### Project wont start. Getting error: java.net.BindException: Address already in use
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May see in console log:
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```
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***************************
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APPLICATION FAILED TO START
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***************************
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Description:
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The Tomcat connector configured to listen on port 8080 failed to start. The port may already be in use or the connector may be misconfigured.
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Action:
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Verify the connector's configuration, identify and stop any process that's listening on port 8080, or configure this application to listen on another port.
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```
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This means another application is already running on port 8080. You need to find and stop the other application.
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#### Database tables missing in H2 Database console.
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By default Spring Boot will configure the datasource as ```jdbc:h2:mem:testdb```
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However, if running the H2 database console for the first time, the datasource URL is ```jdbc:h2:~/test```
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What happens is the H2 database console is connecting to a different instance of the H2 database console, thus you will
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not see the database tables.
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**Solution:** When connecting in the H2 Database Console, change the JDBC URL to ```jdbc:h2:mem:testdb```
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#### Multi-Module Maven Project has error 'can't find Main class'
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Spring Boot is trying to build an executable fat JAR with dependencies for a module that should be a normal JAR, thus looking
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for the main class for the JAR manifest file.
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**Solution:**
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You need to tell the Spring Boot Maven Plugin to **not** repackage the jar.
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Add the following property to the Maven module you wish packaged as a normal jar.
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```xml
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<properties>
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<spring-boot.repackage.skip>true</spring-boot.repackage.skip>
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</properties>
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```
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**Note:** For Spring Boot 2.1 or Higher! This configuration has changed from earlier versions of Spring Boot.
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#### Getting an error, but cannot find what is different from lesson source code.
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Sometimes it can be a very small difference. You can use Git to report the differences between your code and the example
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source code for the lesson.
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**Note:** This will only work if you've forked the original source code example to your GitHub repository.
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1. Commit all of your changes.
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2. Add remote for original repo - ```git remote add sfgRepo github_url```
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3. Fetch remote - ```git fetch sfgRepo```
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4. Run diff - ```git diff HEAD..sfgRepo/master``` <- update branch name from master to desired branch for lesson
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#### Error - java.lang.NoClassDefFoundError: javax/xml/bind/JAXBException
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You are running Java 9+ and have not added the JAXB dependencies.
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Add the following dependencies to your Maven POM:
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```xml
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<properties>
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<jaxb.version>2.3.0</jaxb.version>
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</properties>
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<dependencies>
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<dependency>
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<groupId>javax.xml.bind</groupId>
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<artifactId>jaxb-api</artifactId>
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<version>${jaxb.version}</version>
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</dependency>
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<dependency>
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<groupId>com.sun.xml.bind</groupId>
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<artifactId>jaxb-core</artifactId>
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<version>${jaxb.version}</version>
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</dependency>
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<dependency>
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<groupId>com.sun.xml.bind</groupId>
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<artifactId>jaxb-impl</artifactId>
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<version>${jaxb.version}</version>
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</dependency>
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</dependencies>
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```
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#### JUnit 5 Tests are not running from Maven
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There are several reasons for this, and a lot of bad advice on the internet.
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Please see this [blog post!](https://springframework.guru/why-your-junit-5-tests-are-not-running-under-maven/)
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#### Spring Pet Clinic - CSS is not rendered, page is not styled.
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The CSS resources are generated with Maven. Thus if the project is cleaned, not built, or re-generated with IntelliJ
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the CSS resources will not exist.
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**Solution:** Just build the project with Maven. ```mvn clean package```
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#### Error 'No qualifying Bean of type [Java class name] found for dependency...'
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Spring is looking for a bean of a specific type in the context, but is unable to find it. Error is because Spring
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has not been configured to create a bean for the Java class indicated in the message.
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This may be due to several different reasons, but when troubleshooting - keep in mind Spring is telling you
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that Java class is missing from the context. You need to tell Spring to create a bean of that type.
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Try the following:
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1. Make sure you have a bean of the type configured.
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* Is the missing Java class annotated with a Spring stereotype - @Component, @Controller, @RestController, @Service, @Repository?
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* Or has the bean been declared in a Java configuration class using the @Bean annotation?
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2. Is the package of the Java class or configuration class being scanned?
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* By default, Spring Boot will do a component scan of the package of the main application class, and all sub-packages.
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A common mistake is to create a package outside of this package structure. (thus, Spring does not 'see' the configuration)
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* If the component is not under the package of the main application class, use the @ComponentScan annotation. See this
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[link](https://springframework.guru/spring-component-scan/) for additional information.

‎pom.xml

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<parent>
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<groupId>org.springframework.boot</groupId>
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<artifactId>spring-boot-starter-parent</artifactId>
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<version>2.0.0.M5</version>
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<version>2.1.2.RELEASE</version>
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<relativePath/> <!-- lookup parent from repository -->
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</parent>
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