Recognizing extended class object

Question

In Java, I have a class Num, and a few classes that extend Num, like Num_int and Num_double. I want to know whether it's possible for a method to recognize whether a given Num object is a Num_int or not.

I have the following code:

void test(Num_int x) {
  System.out.println("int");
} // test
void test(Num x) {
  System.out.println("other");
} // test

Num_int A = new Num_int( );
Num B     = new Num_int( );
Num C     = new Num_double( );

test(A); // prints "int"
test(B); // prints "other"
test(C); // prints "other"

Unfortunately, the method "test" only prints "int" when A is given as argument. I wan't the function to also print "int" when B is passed, since B is created via Num B = new Num_int( );. Is this possible?

Thanks.

Answer 1

if (x instanceof Num_int) {
  System.out.println("int");
} else {
  System.out.println("other");
}