[GROOVY-4526] NullObject paradoxes

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.7.5, 1.8-beta-2
• Fix Version/s: 1.8.0
• Component/s: groovy-runtime
• Assignee: Jochen Theodorou
• Reporter: Nikita Y Volkov
• Created: 23/Nov/10 23:55
• Updated: 03/Nov/23 17:38
• Resolved: 21/Aug/23 08:49

Description

def theNull = NullObject.getNullObject()

assert theNull 	//	first paradox

assert theNull instanceof NullObject
assert theNull.equals(null)
assert theNull != null	//	second paradox

assert null.getClass() == NullObject
assert !(null instanceof NullObject)	//	third paradox

I have bumped into this paradox after debugging the following script:

new File('inexestent-folder/').listFiles().with { files ->
	assert files
	assert files in NullObject

	println "This shouldn't happen"
}

Issue Links

• relates to: GROOVY-11196 ambiguous method error for tap on null receiver