InstanceOF

nogono · #1 (**permalink**) 11-28-2007, 02:06 PM

In java what do you mean by ....

instanceof..I tried to understand from internet...but was unable to understand....So can u please explain me with an example.

HelloWorld · #2 (**permalink**) 11-28-2007, 05:33 PM

The simplest way to say is that, this is the way you cast an Object in java:

Code:

class Point { int x, y; }
class Element { int atomicNumber; }
class Test {
    public static void main(String[] args) {
        Point p = new Point();
        Element e = new Element();
        if (e instanceof Point) { // compile-time error
            System.out.println(“I get your point!”);
            p = (Point)e;     // compile-time error
        }
    }
}

It's some type of typecasting, this case wouldn't work because Element is not A Point.. so in order to fulfill that requirement, you need to create:

Code:

class Point extends Element { int x, y; }

As you see in the inheritance, Element is having Point as a parent, and Element is now A Point.

itgalary · #3 (**permalink**) 05-30-2008, 08:08 AM

A instanceOf B means ::: If A ia an object of class B.

Class B
{
something...
}
class C
{
something...
}
private B a;
private C d;

so a instanceOf B will be true
while a instanceOf C is not true... since a is not object of class C.

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