The instanceof operator can be used to test if an object is of a specified type. It is normally used in an if statement and its syntax is this.
if (
objectReference
instanceof
type
)
where objectReference references an object being investigated. For example, the following if statement returns true.
String s = "Hello";
if (s instanceof java.lang.String)
However, applying instanceof on a null reference variable returns false. For example, the following if statement returns false.
String s = null;
if (s instanceof java.lang.String)
Also, since a subclass “is a” type of its superclass, the following if statement, where Child is a subclass of Parent, returns true.
Child child = new Child();
if (child instanceof Parent) // evaluates to true