The following very simple code is behaving really strangely.

Could anyone please tell me if this is an issue in Groovy or something I am not doing properly (I would like to vote for the latter, yet...).


In Java



System.out.println("init x: " + x);


In Groovy


println '1 = ' + x

x = 'two'

println '2 = ' + x




init x: one  <- initial value assignement OK


1 = one      <- successfully accessing ‘x’ from within the compiled script OK  

                the Groovy script has picked up the value of the Java variable;

                the implicit getX() has been called


2 = one                <- should be ‘two’ as per Groovy code (second line)

                but is unchanged ???  


It seems that the Groovy script can’t change the value of ‘x’ (can’t access setX()). However there is no compilation error (‘x’ is not read-only)

When implementing getX/setX methods, only the getter is called (in both print statements, line 1,3) but during the assignment instruction (line 2), the setter is silently ignored (the value of ‘x’ remains ‘one’ instead of ‘two’.


The Java/Groovy binding is operational since the ‘one’ value of ‘x’ in the Java  base class is successfully retrieved. So could anyone please tell me where the issue is?

The confusing part is that even within in the Groovy context alone, the assignment ‘x=’two’ is not honoured (and yet there are no compilation/runtime error)


Note that I tried all combinations of setters/getters/visibility and can at the best read but never modify the variable ‘x’. The same behaviour occurs with using the GroovyScriptEngine or GroovyClassLoader


Thank you very much in advance for your help.





PS: (I am not sure if my previous message went through as I was still in the mailing list registration process, apologies if it is a duplicate)


Full code:


import org.codehaus.groovy.control.CompilerConfiguration;

import org.codehaus.groovy.control.customizers.ASTTransformationCustomizer;


import groovy.lang.Binding;

import groovy.lang.Closure

import groovy.lang.GroovyClassLoader;

import groovy.lang.GroovyShell;

import groovy.transform.CompileStatic;;


abstract class GroovyDemoScript extends Script


    public String x;


    public GroovyDemoScript()



           System.out.println("init x: " + x);



    public static void main(String...args) throws Throwable



           // Compilation configuration

           CompilerConfiguration configuration = new CompilerConfiguration();

           configuration.addCompilationCustomizers(new ASTTransformationCustomizer(CompileStatic.class));


                                // make sure we use the Java base class where ‘x’ is defined



           GroovyShell shell = new GroovyShell(this.getClass().getClassLoader(), new Binding(), configuration);


           // source code

           String scriptSource= "println '1 = ' + x; x = 'two'; println '2 = ' + x\n";


           // compile the source code and run the compiled script

           GroovyDemoScript compiledScript = shell.parse(scriptSource);





Switchboard: +44 (0)113 394 6020

Technical Support: +44 (0)113 394 6030

Lhasa Limited, a not-for-profit organisation, promotes scientific knowledge & understanding through the development of computer-aided reasoning & information systems in chemistry & the life sciences. Registered Charity Number 290866. Registered Office: Granary Wharf House, 2 Canal Wharf, Leeds, LS11 5PS. Company Registration Number 01765239. Registered in England and Wales.

This communication, including any associated attachments, is intended for the use of the addressee only and may contain confidential, privileged or copyright material. If you are not the intended recipient, you must not copy this message or attachment or disclose the contents to any other person. If you have received this transmission in error, please notify the sender immediately and delete the message and any attachment from your system. Except where specifically stated, any views expressed in this message are those of the individual sender and do not represent the views of Lhasa Limited. Lhasa Limited cannot accept liability for any statements made which are the sender's own. Lhasa Limited does not guarantee that electronic communications, including any attachments, are free of viruses. Virus scanning is recommended and is the responsibility of the recipient.