[SPARK-26813] Consolidate java version across language compilers and build tools

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 3.0.0
• Component/s: Build
• Assignee: Chenxiao Mao
• Reporter: Chenxiao Mao
• Created: 02/Feb/19 04:32
• Updated: 04/Feb/19 14:59
• Resolved: 04/Feb/19 14:56

Description

The java version here means versions of javac source, javac target, scalac target. They could be consolidated as a single version (currently 1.8)

	javac	scalac
source	1.8	2.12/2.11
target	1.8	1.8

The current issues are as follows

• Maven defines a single property to specify java version (java.version) while SBT build defines different properties for javac (javacJVMVersion) and scalac (scalacJVMVersion). SBT should use a single property as Maven does.
• Furthermore, it's better for SBT to refer to java.version defined by Maven. This is possible since we've already been using sbt-pom-reader.

Issue Links

• links to: GitHub Pull Request #23724