Upon returning from vacation, the chief abbot of the Laughing Monkey Clan found his temple in a state of panic and disarray. The financial system they had just modified was throwing NullPointerExceptions for all new customers. These users, disquieted in the extreme, were terminating their accounts after barely a day.
With some difficulty the abbot traced the problem to a method whose stated purpose was to return a List of the user’s transactions. If there were no transactions it returned null, rather than the empty list.
“Bring me the monk who wrote this method,” he told the temple guards. “And also the monk whose code invokes it.”
The first monk, who was the elder of the two, declared that the blame should be placed squarely at the feet of the second. “My Javadoc was clear in the extreme. It is not my fault that he did not check for nulls.” The second monk hung his head in shame and said nothing.
The abbot clapped his hands and two tall jade urns were set upon the floor, one before each monk. “Your punishments have been written on slips of paper within. Each day you are to remove the first slip your hand touches and obey its decree to the letter, until your urn is empty.”
The younger monk was bade go first. His hand had not gone halfway into the urn when the rustling of paper was heard. Reading the slip, he bowed and left the room.
The elder monk reached deep into his own urn until his fingers brushed the cold bottom. “There are no slips of paper in this urn,” said the monk, the slightest smile playing at the corner of his mouth.
“Neither are there fish, nor ten mountains,” said the abbot.
The elder monk then cried out in pain. The urn fell over and shattered. A scorpion scuttled away across the tiles.
The abbot regarded the dying monk. “All nothings are not equal.”