How Can I Access Subclass Methods from a Superclass Variable in Java?

Accessing Subclass Methods from Superclass

In object-oriented programming, inheritance allows classes to inherit properties and behaviors from their parent classes. However, when accessing methods of subclasses from a superclass variable, some limitations occur.

Consider the following code snippet:

abstract public class Pet {
    ...
}

public class Cat extends Pet {
    private String color;
    public String getColor() { ... }
}

public class Kennel {
    public static void main(String[] args) {
        Pet cat = new Cat("Feline", 12, "Orange");
        cat.getColor(); // Compiler error: getColor() not defined in Pet
    }
}

In the Kennel class, when a Cat object is assigned to a Pet variable, only members defined in Pet are accessible. This includes methods like getName() and getAge(), but not getColor().

To resolve this, there are two options:

1. Declare Variable as Subclass:

Declare the variable as the specific subclass:

Cat cat = new Cat("Feline", 12, "Orange");
cat.getColor(); // Valid, getColor() is defined in Cat

2. Cast Variable to Subclass:

Cast the variable to a known or expected subclass:

Pet cat = new Cat("Feline", 12, "Orange");
((Cat)cat).getColor(); // Valid, getColor() is accessible via casting

Example Implementation:

Here is a corrected version of the Kennel class:

public class Kennel {
    public static void main(String[] args) {
        Cat cat = new Cat("Feline", 12, "Orange");
        System.out.println("Cat's color: " + cat.getColor());
    }
}

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