Groovy == operator

Question

Until now, my understanding was that == is an operator overload for .equals(). However, I recently discovered that

new Integer(1) == new Long(1) // returns true 

whereas

new Integer(1).equals(new Long(1)) // returns false 

so I guess == is not exactly a shorthand for .equals(), so how does it determine equality?

Answer 1

== in Groovy is roughly equivalent to equals(), however, you'll find it's different from Java when comparing different classes with the same value - if the class is Comparable. Groovy also does type casting if possible.

If you check out the code, it looks like ultimately compareToWithEqualityCheck() is executed for ==.