How to call same method from two different classes in java

Question

I have two classes Apple and Orange like this:

public final  class Apple{
    int getJuice();
}
public final class Orange{
    int getJuice();
}

and I cannot change them. I have third class fruitsManeger like this:

class FruitManeger {
     Apple apple;
     Orange orange;

     enum Fruits{
        Apple,Orange
     }

     Fruits favorFruits;    

     int getJoice(){
         if(favorFruits==Fruits.Apple){
               apple.getJuice();
         }else if(favorFruits==Fruits.Orange){
               orange.getJuice();
         } 
     }

}

My Question: what is best way to implement getJuice method in FruitManeger class?.

as you can see if I have a lot of fruits I should add a lot of if else expiration.

of course, I can use reflection to call methods by name but it's not a good idea when getJuice method return an object and you want to do something same with that.

is there any better way?

Solution

is there any better way?

Yes, Refactor that application into a more oop way...

Remember: you cannot Modify Apple or Orange, but OOP allows you extending those classes for sure since they are not final...

class CorrectApple extends Apple implement IJuiceble{
    @Override
    int getJuice();
}
class CorrectOrange extends Orange  implement IJuiceble{
    @Override
    int getJuice();
}

now the

interface IJuiceble{
    int getJuice();
}

and finally the manager:

class FruitManeger {
     private CorrectApple apple;
     private CorrectOrange orange;

     int getJoice(IJuiceble correctfruit){
         return correctfruit.getJuice();
     }
}

Comments

[max]

i cannot change apple and orange class

[KC Wong]

We will just have to ask why you cannot change Apple and Orange... because the huge amount of if/case statements you'd need is a direct result of that. By the way you can use Reflection to handle the returned object as well.... you'd just need more if/case statements.

[max]

because Apple and orange is in java library

[ΦXocę 웃 Пepeúpa ツ]

Apple and Orange are non final classes, extend those then... look my suggested answer please...

[Darshit]

I think you should read about factory design pattern.It is perfect scenario for your question.

[KC Wong]

The question stated, for whatever reason, the classes Apple and Orange cannot be changed, and they don't implement or extend anything.

[Scary Wombat]

a moving target

[ΦXocę 웃 Пepeúpa ツ]

@max well if you dont provide the correct/complete information then this answer is not even going to compile... and my design is now useless....

[ΦXocę 웃 Пepeúpa ツ]

the more fruits you have in the manager the bigger the switch case and the enum....

[jklee]

It's a bad solution, but is a solution for the question. I prefer the interface solution as well.

[ΦXocę 웃 Пepeúpa ツ]

I like the way you approached anyway\

[Turo]

You could still make a CorrectApple that has an Apple.

[TimeTraveler]

Can we achieve same thing using annotations? That would save redefining all classes?

[user2441441]

Question: Should FruitManager also implement IJuicable as a good practice? Should the class FruitManager be called FruitFactory as a good practice? Should we have a List storing all the fruits in FruitManager so we can easily loop through the fruits?