What is the role of instanceof?

Instanceof is a binary operator in Java. It is used to determine whether the object pointed to by a referenced variable is an instance of a class (or interface, abstract class, or parent class, that is, whether the object on the left is an instance of the class on the right of it, and return boolean data.

The common usage is as follows: Result = Object instanceof class. If an object is an instance of class, the instanceof operator returns true. If the object is not an instance of the specified class, or the object is null, false is returned.

Take the following program as an example.

Public class test { Public static void main (string ARGs []) { String S = "hello "; Int [] A = {1, 2 }; If (s instanceof string) System. Out. println ("true "); If (s instanceof object) System. Out. println ("true "); If (A instanceof int []) System. Out. println ("true "); } }

The program running result is:

True True True

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