Is it possible to have multiple jobs or builds in workflow? - circleci

Question

first let me tell you I am a quite beginner with Circleci, so some of my questions might not make too much sense but bear with me.
Recently I published a project of mine in Github PoC Akka FSM, I heard from several friends good things about Circleci and I am trying to use for my project.
Circleci web page created a config.yml for me and it is looking good but I have a complication, my Project is a Gradle Project but it has a dependency to Eclipse .p2 Repositories, which Gradle can't resolve out of the box. So I have a small Maven Project that collects my dependencies from .p2 repository and convert those to a big fat dependency jar.
Now when I locally build, I build first maven project which would place the the dependency in local maven repository, so the Gradle can locate the Artifact from Maven repository.
Now for the reason you might guess this is not working in Github with Circleci's default config.yml, so my question would it be possible to combine a maven build and gradle build in Circleci. Or a define in a prestep for an extra Build.
Otherwise I will try to convert Maven project to Gradle project (I am not sure Gradle would be able to read .p2 repositories).
The following is the Maven Project.
Thx for answers

Answer 1

I solved my Problem and I like to explain here how, in case another complete beginners lands here.
First, if you are complete new to CircleCI please start reading this before anything else, life would be much easier.
CircleCI Concepts
Secondly, this link
CirceCI Sequential Jobs
explains perfectly how Sequential Jobs should work, at the beginning the wordings 'Steps' being under 'Job' and 'Workflow' confused me a lot, I was not sure I have to implement my Maven Step in Job or Workflow, but it seems it must be Workflow.
Third, I was not quite sure how to transfer the Artefacts of Maven Build to Gradle Build, it seems Cache mechanism is responsible for it. When first I read it, a cache in Build System didn't not made too much sense but I think (I am completely speculating) caches in CirceCI is like Java Maps, you put in Job a value with key, next job can pick the value for key (value being here the Artefacts?). So I in my Maven Job, I am saving my Cache with Key "v1-dependencies-{{ checksum "fsm-akka-eclipse-dependencies/pom.xml" }}" and in the next Job, I load it with same key (and additionally v1-dependencies-{{ checksum "build.gradle" }} while I have a feeling if the checksum of 'build-gradle' is not changed CircleCI optimize something) Someone with more experience may be clear that here
Fourth, I was not sure how to say CircleCI to install Maven or Gradle but it seems CircleCI doing it in a magic way. In my previous point, I mentioned the caches to transfer the Artefacts', but for Maven Job, I am telling to save the cache at '.m2' directory which normally Gradle will look for Maven Artefact, may be this is doing the trick or the Cache I can't tell.
If you like the see how my final config.yml looks, you can find it on the link.