Creating References Using Inheritance Hierarchies

public class Animal {
    public String name() { return "Animal"; }
}
public class Bird extends Animal {
    public String name() { return "Bird"; }
}
// Usage:
ArrayList<Animal> zoo = new ArrayList<Animal>();
zoo.add(new Bird());
zoo.add(new Animal());
zoo.add(new Bird());
int count = 0;
for (int i = 0; i < zoo.size(); i++) {
    if (zoo.get(i) instanceof Bird) count++;
}
System.out.print(count);

• A

  3

• B

  2

  check_circle
• C

  0

• D

  1