Groovy method reference for multiple instances

Question

I am migrating from Java to Groovy and having an issue with method references.

In Java, I could do this:

Function<Bean, String> f = Bean::method;
String s = f.apply(new Bean());

I want to implement the same functionality in Groovy. I tried doing:

Function f = Bean.&method
Sting s = f.apply new Bean()

But I got an exception, on the f.apply line:

groovy.lang.MissingMethodException: No signature of method: Bean.method() is applicable for argument types: (Bean) values: [Bean@17483c58]

I know I can do the following to get the method reference for an instance method, but I want to get a generic method for any instance.

MethodClosure f = bean.&method
String s = f()

I want to use this to use the EasyBind library. It allows you to select a JavaFX property with a Function reference. You might have a hierarchy of classes and properties, and to select them, you might do:

property.bind(EasyBind.select(root).select(Root::branch).selectObject(Branch::leaf));

So when any of the values in the tree change, property get's updated with the correct value.

I am able to replace the Bean.&method with {bean -> bean.method} and that works fine. In Java, the Bean::method is actually an alias-type thing for bean -> bean.method.

Answer 1

You can use:

MethodClosure f = { it.method }
String s = f()