Answer / alka

Interface is third way to achieve polymorphism.Because when
you call a method on any interface variable then at run time
it is decided which object method to call.
Ex :
Let there is a Interface A:
public interface A
{
void display();
}

And two classes B and C implement A
class B implements A
{
display()
{
System.out.println("Class B");
}
}

class C implements A
{
display()
{
System.out.println("Class C");
}
}

Then while using interface A..see what will happen
class mainClass
{
public static void main(String args[])
{
A obj = new C();
obj.display();
obj = new B();
obj.display();
}
}

Output : Class C
Class B
So it is clear that while run/execution time it is decided
which display() method to call..i.e class B or class C display()

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