Differences between dependencyManagement and dependencies in Maven

Question

What is the difference between dependencyManagement and dependencies? I have seen the docs at Apache Maven web site. It seems that a dependency def

Answer 1

The documentation on the Maven site is horrible. What dependencyManagement does is simply move your dependency definitions (version, exclusions, etc) up to the parent pom, then in the child poms you just have to put the groupId and artifactId. That's it (except for parent pom chaining and the like, but that's not really complicated either - dependencyManagement wins out over dependencies at the parent level - but if have a question about that or imports, the Maven documentation is a little better).

After reading all of the 'a', 'b', 'c' garbage on the Maven site and getting confused, I re-wrote their example. So if you had 2 projects (proj1 and proj2) which share a common dependency (betaShared) you could move that dependency up to the parent pom. While you are at it, you can also move up any other dependencies (alpha and charlie) but only if it makes sense for your project. So for the situation outlined in the prior sentences, here is the solution with dependencyManagement in the parent pom:

  
    
       
        alpha
        alpha
        1.0
        
          
            zebra
            zebra
          
        
      
      
        charlie 
        charlie
        1.0
        war
        runtime
      
       
        betaShared
        betaShared
        1.0
        bar
        runtime
      
    
  




  
    
      alpha
      alpha  
    
    
      betaShared
      betaShared
      bar 
    
  




  
    
      charlie
      charlie
      war 
    
    
      betaShared 
      betaShared 
      bar