CODEWITHSUNDEEP
groovy
Jan Krakora
Jan Krakora

Reputation: 2610

Class definition within groovy script

Is it possible to create class definitions within a groovy script?

I have a simple script example

class HelloWorld {    
    def name    

    def greet() { 
        "Hello ${name}" 
    }
}    

def helloWorld = new HelloWorld()
helloWorld.name = "Groovy"

println helloWorld.greet()

but I get error like this

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Script1.groovy: 1: Class definition not expected here. Please define the class at an appropriate place or perhaps try using a block/Closure instead. at line: 1 column: 1. File: Script1.groovy @ line 1, column 1.
   class HelloWorld {    
   ^

1 error

at org.codehaus.groovy.control.ErrorCollector.failIfErrors(ErrorCollector.java:309) ~[groovy-all-2.4.3.jar:2.4.3]
at org.codehaus.groovy.control.CompilationUnit.applyToSourceUnits(CompilationUnit.java:943) ~[groovy-all-2.4.3.jar:2.4.3]
at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:590) ~[groovy-all-2.4.3.jar:2.4.3]
at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:566) ~[groovy-all-2.4.3.jar:2.4.3]
at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:543) ~[groovy-all-2.4.3.jar:2.4.3]
at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:297) ~[groovy-all-2.4.3.jar:2.4.3]
at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:267) ~[groovy-all-2.4.3.jar:2.4.3]
at groovy.lang.GroovyShell.parseClass(GroovyShell.java:692) ~[groovy-all-2.4.3.jar:2.4.3]
at groovy.lang.GroovyShell.parse(GroovyShell.java:704) ~[groovy-all-2.4.3.jar:2.4.3]
at groovy.lang.GroovyShell.parse(GroovyShell.java:740) ~[groovy-all-2.4.3.jar:2.4.3]
at groovy.lang.GroovyShell.parse(GroovyShell.java:731) ~[groovy-all-2.4.3.jar:2.4.3

Upvotes: 1

Views: 8909

Answers (2)

Nathan Hughes
Nathan Hughes

Reputation: 96444

Yes, in general it's normal to create class definitions within a script.

I'm not able to reproduce your error, and you don't say how you're running this code. I'm guessing you're trying to use a Groovy script to configure some product (Mule has this feature, for instance). Your problem would seem to be specific to the thing you're trying to configure.

If I try to run the script in groovysh I get "Unknown property" when it tries to define the helloWorld variable using def.

In groovyconsole it works fine, as Dónal says.

If I take your code and put it in a file called HelloWorld.groovy and run that from the command line:

groovy HelloWorld.groovy

then I get

C:\Users\ndh\HelloWorld.groovy: 1: Invalid duplicate class definition of class HelloWorld : The source C:\Users\ndh\HelloWorld.groovy contains at least two definitions of the class HelloWorld. One of the classes is an explicit generated class using the class statement, the other is a class generated from the script body based on the file name. Solutions are to change the file name or to change the class name. @ line 1, column 1. class HelloWorld { ^

1 error

Changing the name of the file to notHelloWorld.groovy works:

c:\Users\ndh>groovy notHelloWorld.groovy
Hello Groovy

but this is not your problem because the stacktrace shows your filename to be Script1.

When I write a script I put the main logic at the top and put helper functions and class definitions toward the bottom. That's just how I organize the code for readability, though.

Upvotes: 1

Dónal
Dónal

Reputation: 187379

This code works fine. You can see for yourself here.

Upvotes: 2

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