How to understand Maven dependency tree

Question

Please excuse if this a dump question but I have searched a lot and couldn't understand how to actually read Maven Dependency tee. I know this command is used to figure out the dependencies but how? This is the result of mvn dependency:tree -Dverbose in my project.

[INFO] +- org.springframework:spring-core:jar:4.0.2.RELEASE:compile
[INFO] |  \- commons-logging:commons-logging:jar:1.1.3:compile
[INFO] +- org.springframework:spring-web:jar:4.0.2.RELEASE:compile
[INFO] |  +- (org.springframework:spring-aop:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- org.springframework:spring-beans:jar:4.0.2.RELEASE:compile
[INFO] |  |  \- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-context:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  \- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] +- org.springframework:spring-webmvc:jar:4.0.2.RELEASE:compile
[INFO] |  +- (org.springframework:spring-beans:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-context:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- org.springframework:spring-expression:jar:4.0.2.RELEASE:compile
[INFO] |  |  \- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  \- (org.springframework:spring-web:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] +- org.springframework:spring-context:jar:4.0.2.RELEASE:compile
[INFO] |  +- (org.springframework:spring-aop:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-beans:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  \- (org.springframework:spring-expression:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] +- org.springframework:spring-aop:jar:3.0.0.RC3:compile
[INFO] |  +- aopalliance:aopalliance:jar:1.0:compile
[INFO] |  +- org.springframework:spring-asm:jar:3.0.0.RC3:compile
[INFO] |  +- (org.springframework:spring-beans:jar:3.0.0.RC3:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  \- (org.springframework:spring-core:jar:3.0.0.RC3:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] +- org.springframework:spring-tx:jar:4.0.2.RELEASE:compile
[INFO] |  +- (org.springframework:spring-beans:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  \- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] +- org.springframework:spring-orm:jar:4.0.2.RELEASE:compile
[INFO] |  +- (org.springframework:spring-beans:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- org.springframework:spring-jdbc:jar:4.0.2.RELEASE:compile
[INFO] |  |  +- (org.springframework:spring-beans:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  |  +- (org.springframework:spring-core:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  |  \- (org.springframework:spring-tx:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] |  \- (org.springframework:spring-tx:jar:4.0.2.RELEASE:compile - omitted for duplicate)
[INFO] +- org.springframework.security:spring-security-core:jar:3.2.2.RELEASE:compile
[INFO] |  +- (aopalliance:aopalliance:jar:1.0:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-aop:jar:3.2.8.RELEASE:compile - omitted for conflict with 3.0.0.RC3)
[INFO] |  +- (org.springframework:spring-beans:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  +- (org.springframework:spring-context:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  +- (org.springframework:spring-core:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  \- (org.springframework:spring-expression:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] +- org.springframework.security:spring-security-web:jar:3.2.2.RELEASE:compile
[INFO] |  +- (aopalliance:aopalliance:jar:1.0:compile - omitted for duplicate)
[INFO] |  +- (org.springframework.security:spring-security-core:jar:3.2.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-beans:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  +- (org.springframework:spring-context:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  +- (org.springframework:spring-core:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  +- (org.springframework:spring-expression:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  \- (org.springframework:spring-web:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] +- org.springframework.security:spring-security-config:jar:3.2.2.RELEASE:compile
[INFO] |  +- (aopalliance:aopalliance:jar:1.0:compile - omitted for duplicate)
[INFO] |  +- (org.springframework.security:spring-security-core:jar:3.2.2.RELEASE:compile - omitted for duplicate)
[INFO] |  +- (org.springframework:spring-aop:jar:3.2.8.RELEASE:compile - omitted for conflict with 3.0.0.RC3)
[INFO] |  +- (org.springframework:spring-beans:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  +- (org.springframework:spring-context:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] |  \- (org.springframework:spring-core:jar:3.2.8.RELEASE:compile - omitted for conflict with 4.0.2.RELEASE)
[INFO] +- javax.servlet:javax.servlet-api:jar:3.1.0:compile
[INFO] +- org.glassfish.jersey.core:jersey-server:jar:2.6:compile
[INFO] |  +- org.glassfish.jersey.core:jersey-common:jar:2.6:compile
[INFO] |  |  +- (javax.ws.rs:javax.ws.rs-api:jar:2.0:compile - omitted for duplicate)
[INFO] |  |  +- (javax.annotation:javax.annotation-api:jar:1.2:compile - omitted for duplicate)
[INFO] |  |  +- org.glassfish.jersey.bundles.repackaged:jersey-guava:jar:2.6:compile
[INFO] |  |  +- (org.glassfish.hk2:hk2-api:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2.external:javax.inject:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2:hk2-locator:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  \- org.glassfish.hk2:osgi-resource-locator:jar:1.0.1:compile
[INFO] |  +- org.glassfish.jersey.core:jersey-client:jar:2.6:compile
[INFO] |  |  +- (org.glassfish.jersey.core:jersey-common:jar:2.6:compile - omitted for duplicate)
[INFO] |  |  +- (javax.ws.rs:javax.ws.rs-api:jar:2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2:hk2-api:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2.external:javax.inject:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  \- (org.glassfish.hk2:hk2-locator:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  +- javax.ws.rs:javax.ws.rs-api:jar:2.0:compile
[INFO] |  +- javax.annotation:javax.annotation-api:jar:1.2:compile
[INFO] |  +- org.glassfish.hk2:hk2-api:jar:2.2.0:compile
[INFO] |  |  +- org.glassfish.hk2:hk2-utils:jar:2.2.0:compile
[INFO] |  |  \- org.glassfish.hk2.external:aopalliance-repackaged:jar:2.2.0:compile
[INFO] |  +- org.glassfish.hk2.external:javax.inject:jar:2.2.0:compile
[INFO] |  +- org.glassfish.hk2:hk2-locator:jar:2.2.0:compile
[INFO] |  |  +- (org.glassfish.hk2.external:javax.inject:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2.external:aopalliance-repackaged:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2:hk2-api:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  +- (org.glassfish.hk2:hk2-utils:jar:2.2.0:compile - omitted for duplicate)
[INFO] |  |  \- (org.javassist:javassist:jar:3.18.1-GA:compile - omitted for conflict with 3.15.0-GA)
[INFO] |  \- javax.validation:validation-api:jar:1.1.0.Final:compile
[INFO] +- com.sun.jersey.contribs:jersey-spring:jar:1.18.1:compile
[INFO] |  +- com.sun.jersey:jersey-servlet:jar:1.18.1:compile
[INFO] |  |  \- com.sun.jersey:jersey-server:jar:1.18.1:compile
[INFO] |  |     \- com.sun.jersey:jersey-core:jar:1.18.1:compile
[INFO] |  \- (org.springframework:spring-aop:jar:3.0.0.RC3:compile - omitted for duplicate)
[INFO] +- commons-dbcp:commons-dbcp:jar:1.3:compile
[INFO] |  \- commons-pool:commons-pool:jar:1.5.4:compile
[INFO] +- org.hibernate:hibernate-core:jar:4.0.1.Final:compile
[INFO] |  +- commons-collections:commons-collections:jar:3.2.1:compile
[INFO] |  +- antlr:antlr:jar:2.7.7:compile
[INFO] |  +- org.jboss.spec.javax.transaction:jboss-transaction-api_1.1_spec:jar:1.0.0.Final:compile
[INFO] |  +- dom4j:dom4j:jar:1.6.1:compile
[INFO] |  |  \- xml-apis:xml-apis:jar:1.0.b2:compile
[INFO] |  +- org.hibernate.javax.persistence:hibernate-jpa-2.0-api:jar:1.0.1.Final:compile
[INFO] |  +- org.jboss.logging:jboss-logging:jar:3.1.0.CR2:compile
[INFO] |  +- org.javassist:javassist:jar:3.15.0-GA:compile
[INFO] |  \- org.hibernate.common:hibernate-commons-annotations:jar:4.0.1.Final:compile
[INFO] |     \- (org.jboss.logging:jboss-logging:jar:3.1.0.CR2:compile - omitted for duplicate)
[INFO] +- cglib:cglib:jar:2.2.2:compile
[INFO] |  \- asm:asm:jar:3.3.1:compile
[INFO] +- mysql:mysql-connector-java:jar:5.1.22:compile
[INFO] +- org.hibernate:hibernate-validator:jar:4.2.0.Final:compile
[INFO] |  +- (javax.validation:validation-api:jar:1.0.0.GA:compile - omitted for conflict with 1.1.0.Final)
[INFO] |  \- (org.slf4j:slf4j-api:jar:1.6.1:compile - omitted for conflict with 1.7.5)
[INFO] +- com.sun.xml.bind:jaxb-xjc:jar:2.2.6:compile
[INFO] +- com.sun.xml.bind:jaxb-impl:jar:2.2.6:compile
[INFO] +- javax.xml.bind:jaxb-api:jar:2.2.6:compile
[INFO] +- javax.servlet:jstl:jar:1.2:compile
[INFO] +- org.apache.tomcat:jsp-api:jar:6.0.32:provided
[INFO] |  +- org.apache.tomcat:el-api:jar:6.0.32:provided
[INFO] |  \- org.apache.tomcat:servlet-api:jar:6.0.32:provided
[INFO] +- log4j:log4j:jar:1.2.15:compile
[INFO] |  \- javax.mail:mail:jar:1.4:compile
[INFO] |     \- javax.activation:activation:jar:1.1:compile
[INFO] +- org.slf4j:slf4j-api:jar:1.7.5:compile
[INFO] +- org.slf4j:slf4j-simple:jar:1.6.4:compile
[INFO] |  \- (org.slf4j:slf4j-api:jar:1.6.4:compile - omitted for conflict with 1.7.5)
[INFO] \- org.slf4j:slf4j-log4j12:jar:1.7.5:compile
[INFO]    +- (org.slf4j:slf4j-api:jar:1.7.5:compile - omitted for duplicate)
[INFO]    \- (log4j:log4j:jar:1.2.17:compile - omitted for conflict with 1.2.15)
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 6.667 s
[INFO] Finished at: 2014-03-12T14:37:46+01:00
[INFO] Final Memory: 9M/16M
[INFO] ------------------------------------------------------------------------

As marked as solution in this question: IncompatibleClassChangeError: class ClassMetadataReadingVisitor has interface ClassVisitor as super class how can I check for the dependent jars and conflicts?

Answer 1

The answer you linked to says that you should look for a version conflict between spring-core and spring-asm.

If you search for these libraries in the tree, you'll find that most of Spring components including spring-core are 4.0.2.RELEASE, whereas spring-asm is 3.0.0.RC3. Also you can see that offending spring-asm is a transitive dependency of the following top-level dependency:

[INFO] +- org.springframework:spring-aop:jar:3.0.0.RC3:compile

So, now you need to find it in pom.xml and correct its version.

Answer 2

... It's a dependency tree. The things below a listing are dependencies of their parent.

[INFO] +- org.springframework:spring-core:jar:4.0.2.RELEASE:compile
[INFO] |  \- commons-logging:commons-logging:jar:1.1.3:compile

Spring-core depends on commons-logging.

[INFO] +- org.glassfish.jersey.core:jersey-server:jar:2.6:compile
[INFO] |  +- org.glassfish.jersey.core:jersey-common:jar:2.6:compile
[INFO] |  |  +- (javax.ws.rs:javax.ws.rs-api:jar:2.0:compile - omitted for duplicate)
[INFO] |  |  +- (javax.annotation:javax.annotation-api:jar:1.2:compile - omitted for duplicate)

Jersey-server depends on jersey-common. Jersey-common depends on rs-api, annotation-api, etc.