Recommended JDK for WPILIB 2020

We are using 11.0.2 right now, but is there any advantage to using the latest jdk?

The JDK included in the installer is the only supported JDK by the WPILib team.

Java 13 includes many interesting features but it may be more trouble than it is worth upgrading.

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While Java does well with backward compatibility, i think using the supported version is best.

If you do use 13, make sure you compile in java 11 mode

I assume JDK 11 is the supported JDK, based on the responses in this thread (I haven’t gone through the installation yet). I’d like to add another reason you’d not want to use Java 12 or 13. Only Java 11, 14, 17, etc. are long term support releases. Oracle drops public support for Java 13 in March (in the middle of competition season). Source: https://en.wikipedia.org/wiki/Java_version_history. It’s probably a bad idea to use a software product unsupported by both WPILib and its original vendor.

Correct it is java 11

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which jdk is included?

Java 11.0.4

One thing that wasn’t obvious to me, is that when installing the WPI tool suite, I needed to be connected to the Rio, such that the JDK was downloaded to the RIO.

Was that documented somewhere? If so, I must have missed it.

Also, this means that for each of my team’s Rios, I’ll need to re-install the tool suite while connected to each Rio. Is there any harm in that, or is there another way to push the jdk to the rio?

You do not need to be connected to a roboRIO when installing WPILib. When you try to deploy robot code for the first time after flashing a roboRIO, WPILib will check for java on the rio and if it doesn’t exist, install it. This copy of the java runtime is stored on your computer when you install WPILib.

Ok, thanks. That didn’t appear to happen the 1st time I deployed the code. The Rio console was saying it couldn’t find /java

I’ll try again on a fresh rio and take a closer look at what happens.

Maybe the error message said Java cannot be found on your computer.

Perhaps - I’ll take a look tonite when I’m at the build session.