[FIXED] Should I write repositories in my pom.xml?

Issue

I am new to Maven. If I start new project with Maven, should I know any repository URLs for it to work?

For example, this Hibernate tutorial http://docs.jboss.org/hibernate/core/3.3/reference/en/html/tutorial.html says about how to create a sample project with pom.xml text. But this pom.xml does not contain any repositories.

So, my m2eclipse plugin says, for example Project build error: 'dependencies.dependency.version' for org.hibernate:hibernate-core:jar is missing., for all dependency tag in pom.xml

Is this because of repositories absence?

Where to know repositories URLs? Is there one big repository? Why doesn't it included by default?

UPDATE 1 It is said here, that Maven should use "central" repository by default: http://maven.apache.org/guides/introduction/introduction-to-repositories.html

I have searched there for hibernate-code artifact and found it. So, this artifact IS in central repository. By my maven says dependency not found. Hence it doesn't use it's central repository. Why?

Solution

Apparently your Hibernate dependency is missing <version> tag:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-entitymanager</artifactId>
    <version>3.6.9.Final</version> <!-- this line is missing -->
</dependency>

Note that you don't have to specify version of dependencies previously declared in <dependencyManagement>.

Old answer:

Every build script (not only with Maven) should be reproducible and independent from environment. Standard pom.xml (called super pom), which every pom.xml inherits from, already defines main Maven central repository:

<repositories>
  <repository>
    <id>central</id>
    <name>Maven Repository Switchboard</name>
    <layout>default</layout>
    <url>https://repo1.maven.org/maven2</url>
    <snapshots>
      <enabled>false</enabled>
    </snapshots>
  </repository>
</repositories>

You don't have to define this repository, and you don't have to define any others if all your dependencies are there. On the other hand if you are using some external repositories, you must add them to pom.xml, so that every developer is always able to build.

The bottom line is: if you can build the project having a completely empty repository, your pom.xml is fine.

Answered By - Tomasz Nurkiewicz