What is instanceof ?

> instanceof means what the word means, it returns true

> or false if the insance is a instance of the given

> class or not. This means if e.getSource() is an

> insance of the class JButton the insanceof returns

> true. insanceof is used to ask an object if it is an

> instance of a class if you don't no the class of this

> object.

Very good definition

t1052499 at 2007-7-6 20:22:40 >

> To add, it also checks whether the instance is of

> JButton or the sub classes of JButton.

More precisely, "<relex> instanceof <typeref>" is true if the "(<typeref>) relex" casting works. It works if the <relex> has the type <typeref> itself, or <relex> has the type of a direct of indirect subclass of <typeref>, or if the class which is the type of <relex>, implements the interface <typeref> (directly, of due to the inheritance).

That is, true if the left expression (which is an expression) could be cast to the class/interface shown on the right.

But don't forget, if it is obvious during compiling that it cannot be true, then a compile time error occurs.

ivanhu at 2007-7-6 20:22:40 >