How to set the Java version in JShell?

Question

I'm using JShell from JDK 11 to experiment some behaviors with generics.

I would like to set the interpreted java version to version 8. This would allow me to have the same type inference behaviors as defined in the Java Language Specification 8.

How can I do it?

I really doubt jshell is meant for something like that. – Naman Oct 17 '18 at 01:38 — Naman, Oct 17 '18 at 01:38

score 1 · Answer 1 · answered Oct 16 '18 at 21:18

The flag you would like to apply is:

"-source 8"

The way to pass this onto the compiler behind JShell would be:

"jshell -C "-source 11"

... But it won't work. I tried it just now, and the Jshell fails to parse this with an exception. It should not be the case, so I looked into the code of the Arguments class that throws the error. It turned out that javac options are grouped into different categories, and only the BASIC commands are allowed via JShell (com.sun.tools.javac.main.Option.java:1308).

Setting the source flag does not belong to this group, so the validator throws it out and the setting will not be applied.

If you want to verify this, you can try to pass a BASIC type of param to the javac like "-p", and you will see it correctly passed.

score 0 · Answer 2 · answered Oct 16 '18 at 19:39

0

It isn't possible, JShell tool use Java Platform Module System (JPMS) that is a java 9 feature.

answered Oct 16 '18 at 19:39

pierDipi

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Can you elaborate on why JPMS is an obstacle to interpret expressions issued in JShell as Java 8 source code? – Ortomala Lokni Oct 16 '18 at 19:51

How to set the Java version in JShell?

2 Answers2