Currently, Java Linter is disabled in Jenkins tests.
However, as of today, Spark has 721 java files with 97362 code (without blank/comments). It's about 1/3 of Scala.
This issue aims to take advantage of Travis CI to handle the following static analysis by adding a single file, `.travis.yml` without any additional burden on the existing servers.
- Java Linter
- JDK7/JDK8 maven compile
Note that this issue does not propose to remove some of the above work items from the Jenkins. It's possible, but we need to observe the Travis CI stability for a while. The goal of this issue is to removing committer's overhead on linter-related PRs (the original PR and the fixation PR).
By the way, historically, Spark used Travis CI before.