Java:InstanceOf

lastmod 2020-01-15created 2020-01-151 edits

Explanation of the JAVA instanceof operator

• http://arabiannight.tistory.com/313

If the result of an instanceof operation for some type is true, it means a cast to the checked type is possible.

• If the reference variable can use more members than the instance has, it cannot be used.
• If the reference variable can use fewer members than the instance has, it can be used. (Equal is also O).
• Therefore, an ancestor's reference variable can refer to instances of all its descendants.
• ancestor reference variable instanceof descendant instance (always O).
• Object o instanceof descendant instance (always O).
• If you create an empty descendant Class as in example No. , descendant reference variable instanceof ancestor instance (possible O).

See also

• Java