JDK distributions

Since Java 11 Oracle has changed the licensing of its Java SE distribution: it is no longer free for commercial use. Oracle's OpenJDK is still free for commercial use. It has the same functionality (although some tools may be missing) but does not get updates once the next version is out (after 6 months). The community, led by RedHat is however updating LTS (Long Term Support) java distributions (8, 11...). A good distribution is AdoptOpenJDK. Several other companies are offering distributions and paid support. You can find a good summary of this on the JetBrains blog.

If you want to download a prebuilt javadoc for local use, you currently have to download it from the oracle Java SE distribution.

AdoptOpenJDK gives you a choice between Oracle's HotSpot VM and OpenJ9 VM, an Eclipse incubator project, based on VM code donated by IBM.

Differences between AdoptOpenJDK en Oracle OpenJDK are  summarized in the table below:

Oracle JDK 8 proprietary component	Alternative component	OpenJDK 8	OpenJDK 11
Java Web Start	IcedTea-Web	yes	no
JavaFX	OpenJFX	no	no (coming soon)
T2K font rendering engine	Freetype	yes	yes
Monotype Lucida fonts	Relicensed Lucida fonts	no (coming soon)	no (coming soon)
Ductus 2D renderer	Pisces/Marlin	yes (Pisces)	yes (Marlin)
Kodac Color Matching System (KCMS) library	LCMS	yes	yes
SNMP	Use JMX (or SNMP4J)	yes (not bundled)	yes (not bundled)
Sound drivers	Use Windows sound drivers	yes (not bundled)	yes (not bundled)
Java Flight Recorder (JFR)	Java Flight Recorder	no (coming soon)	yes
Java Mission Control (JMC)	Use JDK Mission Control	no (coming soon)	no (coming soon)