为什么 Eclipse 给我“groovy.lang.GroovyObject 无法解析”？

Question

Specs: Linux Mint 18.3, Eclipse 2019-06, Groovy 2.5.8, Java 11

I started a Groovy project, and created a package "test" under the "source folder". Under test I put a file, "test.groovy". This file looks like this:

package test

It's got a horrid white-cross-in-a-red-box. The error message is:

Multiple markers at this line: - The type groovy.lang.MetaClass cannot be resolved. It is indirectly referenced from required .class files - The type groovy.lang.GroovyObject cannot be resolved. It is indirectly referenced from required .class files

I have tried multiple strategies: restarting Eclipse, cleaning the project, removing and putting back the JRM for the project. Nothing doing.

There are a few cases of this error when I Google, but mostly they appear to be from years and years ago, on an active bug list, so I presume resolved.

Any ideas what's going wrong?

NB according to my notes, I have had this problem before a couple of times with Gradle projects, and the problem was resolved by going Gradle --> Refresh for the project. But this is a (pure) Groovy project, not Gradle, and the "Refresh" option is not available.

By the way, when I look at this problem in the "Problems" the error type is said to be "Java Problem".

later

It's been suggested that the cause might be Java 11. This is an interesting idea. However, Groovy 2.5.x in itself is not incompatible with Java 11. Firstly, I have no problem running this at the CLI, and no problem with Eclipse-based Gradle projects configured with Java 11 and Groovy 2.5.x, using Groovy as the language of the app and testing files. Crucially, of course, the Gradle wrapper chooses its own Groovy version, and in such circs the user chooses their own Groovy version for their executables as a dependency in build.gradle . So Eclipse Groovy-handling is mercifully "bypassed".

I am thus beginning to suspect that the Groovy-Eclipse add-in may be the culprit. Amazingly enough, and I was surprised by this, I downloaded and set up the 2019-12 Eclipse package, completely separately, and tried to create a Groovy project in it. Even after several attempts to install both the "release" and "snapshot" versions of Groovy-Eclipse for this version of Eclipse (ie here ), I cannot start the simplest of Groovy projects in that IDE.

So my suspicions are circling around this theory that Groovy-Eclipse is unable to work properly with Java 11. Only problem is that you might expect to find such a bug as one of the issues , but there is nothing.

Answer 1

Add "requires org.codehaus.groovy;" to your module-info.java