What's wrong with this example of Java property inheritance?

Question

Inheritance.java

public class InheritanceExample {
  static public void main(String[] args){
    Cat c = new Cat();
    System.out.println(c.speak());

            


        

Answer 1

You cannot override class fields, only methods. The sound field in your Dog and Cat classes is actually hiding the sound field in the Animal superclass.

You can, however, access superclass fields from subclasses, so you could do something like this:

public class Dog extends Animal {
  public Dog() {
    sound = "woof";
  }
}

public class Cat extends Animal {
  public Cat() {
    sound = "meow";
  }
}

Or, you can make the Animal class abstract, and declare the speak method abstract too, then define it in subclasses:

public abstract class Animal {
  public abstract String speak();
}

public class Dog extends Animal {
  public String speak {
    return "woof";
  }
}

public class Cat extends Animal {
  public String speak {
    return "meow";
  }
}