Question

I am trying to create an Object array (Object[]) to be passed to a method (IDescriptor):

Object[] newValues = {
  Boolean.TRUE
}
descriptor.setParameters(newValues)

The particular descriptor expects the first value in the array to be a java.lang.Boolean object. However, it seems Groovy is converting to its own boolean class, and when I run the code (the above is not the full code), the descriptor reports that the first Object in the array is not a java.lang.Boolean object.

Not that it is very informative, this is the stacktrace:

org.openscience.cdk.exception.CDKException: The first parameter must be of type Boolean
        at org.openscience.cdk.qsar.descriptors.molecular.AromaticAtomsCountDescriptor.setParameters(AromaticAtomsCountDescriptor.java:118)

When I add an assert (repeated in the error), I get this error:

assert newValues[0] instanceof java.lang.Boolean
       |        |   |
       |        |   false
       |        AromaticAtomCountDescriptorParams$_run_closure3@1cc5069
       [AromaticAtomCountDescriptorParams$_run_closure3@1cc5069]

How can I make sure Groovy uses the Java Boolean class in the array, instead of its own richer class?

Answer 1

Use the correct braces:

Object[] newValues = [ true ]

You used {} which creates a closure. That also works because closures have a lot of special abilities but they aren’t lists are arrays. So Groovy wraps the single element on the right hand side in a list and then assigns the array newValues.