instanceof operator

[Abhishek Reddy]

<reference>instanceof <detination type>

the compile time check deternines whether a reference of source type and reference of destination type can denote objects of the reference type that is a commin subtype of both source type and destination type in the type hierarchy

at run time it is the actual object denoted by reference that determines the out come fo the operation

iam unable to understand this(especially compile time) kindly expalin this with an example..

thanks in advance

[Gowher Naik]

class Base{
}
class Child extends Base{
}
class Test {
public static void main(String... args){
Base b=new Child();//line 7
System.out.println(b instanceof Child);//true line 8
}

}

Check code above
Try to understand line 7 and line 8 you will get your answer.

[Henry Wong]

iam unable to understand this(especially compile time) kindly expalin this with an example..

During compilation, the compiler will do a check to see if the operation even has a chance of returning true... for example... if you are checking a StringBuffer reference to see if it is an instance of String, the compiler will complain.

The reason is, it is not possible for a reference that is holding an StringBuffer object to hold an object that is also a String.

Henry

[wise owen]

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