Is there a way to use overridden function in base class? (In Java)

Question

I tried to implement a function in a base class which using the function of the childs (defiend as a abstract function in the base class). I think an example will demonstrate the problem in the best way.

abstract class Animal{
   public void doSomthing(){
      this.sound();
   }

   protected abstract void sound();
}

class Dog extends Animal{
   @Override
   protected void sound(){ 
   System.out.println("WAF"); 
 }
}

now when I tried to get the element in run time (by factory method which looks like: Animal factory method("Dog);) and call to the doSomthing method I got exception because it goes to the abstract method, my question is if there is any way the bypass this or another solution for this problem.

What exception did you get? What was the expected behavior? What actually happened? — Shloim, Dec 25 '19 at 15:24
`AbstractMethodError`? If so, try recompiling all of your source code/delete all the class files. — Tom Hawtin - tackline, Dec 25 '19 at 15:26
The excepted behavior is that the instance will invoke the method **doSomthing** but when it will pass over the code of the function it will invoke the **sound** method of the child class ("Dog") — Lupidon, Dec 25 '19 at 15:28
`this.sound` is not valid. You need to *call the method*: `this.sound()` — QBrute, Dec 25 '19 at 15:32
If you expect an answer, then give us what we need. where is your factory class? we are not sure what your factory method is doing. Also, update your `Animel` class to not have compilation errors. `this.sound` wouldn't do anything but give error — Sunil Dabburi, Dec 25 '19 at 15:33
Your code contain some compilation error. this.sound should be this.sound(). Just share the factory code. Your Factory should return something like Animal a = new Dog(); Then it will work as expected. — dassum, Dec 25 '19 at 15:34
@Tom Hawtin - tackline Thank you, its resolved the problem :) — Lupidon, Dec 25 '19 at 15:41
@CoderIL - If one of the answers resolved your issue, you can help the community by marking it as accepted. An accepted answer helps future visitors use the solution confidently. Check https://meta.stackexchange.com/questions/5234/how-does-accepting-an-answer-work to learn how to do it. — Arvind Kumar Avinash, May 28 '20 at 19:24

score 2 · Accepted Answer · answered Dec 25 '19 at 15:36

 class myMain
{
   public static void main(String[]args)
   {
    Animal doggo = new Dog(); // create object for dog
    doggo.animalSound(); // call the sound for dog

   }
}
    class Animal 
{
  public void animalSound() 
  {
    System.out.println("The animal makes a sound");
  }
}
class Dog extends Animal
{
   public void animalSound()
   {
     System.out.println("The Dog Says bow wow! "); 
   }
}

score 1 · Answer 2 · answered Dec 25 '19 at 15:48

I do not see any problem with the approach you have mentioned in the description of your question. Maybe you are doing some other mistake. Check the following working code:

abstract class Animal {
    public void doSomthing() {
        sound();
    }

    protected abstract void sound();
}

class Dog extends Animal {
    @Override
    protected void sound() {
        System.out.println("WAF");
    }
}

class AnimalFactory {
    static Animal animal;

    public static Animal factoryMethod(String animalName) {
        if ("Dog".equals(animalName)) {
            animal = new Dog();
        }
        return animal;
    }
}

class Main {
    public static void main(String[] args) {
        Animal animal = AnimalFactory.factoryMethod("Dog");
        animal.sound();
    }
}

Output:

WAF

score 0 · Answer 3 · answered Dec 25 '19 at 15:55

0

The call to child class method from super class can be done. Refer code snippet mentioned in below link: Can a Parent call Child Class methods?

answered Dec 25 '19 at 15:55

Ashish Goyal

9
2

Is there a way to use overridden function in base class? (In Java)

3 Answers3