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?

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. — KC Wong
– KC Wong, Commented Nov 30, 2016 at 5:59
Apple and Orange are non final classes, extend those then... look my suggested answer please... — ΦXocę 웃 Пepeúpa ツ
– ΦXocę 웃 Пepeúpa ツ, Commented Nov 30, 2016 at 6:02
I think you should read about factory design pattern.It is perfect scenario for your question. — Darshit
– Darshit, Commented Nov 30, 2016 at 6:06

ΦXocę 웃 Пepeúpa ツ · Accepted Answer · 2016-11-30 06:48:14Z

15

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();
     }
}

edited Nov 30, 2016 at 6:48

answered Nov 30, 2016 at 5:55

ΦXocę 웃 Пepeúpa ツ

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5 Comments

Scary Wombat Over a year ago

a moving target

ΦXocę 웃 Пepeúpa ツ Over a year ago

@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....

Turo Over a year ago

You could still make a CorrectApple that has an Apple.

TimeTraveler Over a year ago

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

user2441441 Over a year ago

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?

jklee · Accepted Answer · 2016-11-30 06:11:38Z

0

You can use switch instead of if/else.

class FruitManager {
    Apple apple;
    Orange orange;

    enum Fruits {
        Apple, Orange
    }

    Fruits favorFruits;

    int getJoice() {
        switch (favorFruits) {
        case Apple:
            apple.getJuice();
            break;
        case Orange:
            orange.getJuice();
            break;

        default:
            System.err.println("Fruit not found. " + favorFruits);
        }
    }

answered Nov 30, 2016 at 6:11

jklee

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3 Comments

ΦXocę 웃 Пepeúpa ツ Over a year ago

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

jklee Over a year ago

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

ΦXocę 웃 Пepeúpa ツ Over a year ago

I like the way you approached anyway\

Community · Accepted Answer · 2017-05-23 12:10:51Z

-1

By referring this Answer

interface IScalable {
   void setScale(int scale);
   int getScale();
}

class DataSizeAction extends EncoderAction implements IScalable {
   ...
}

class SomeoneElse {
   private int scale = 2;

   public void setScale(IScalable scalable) {
      scalable.setScale(this.scale);
   }
}

edited May 23, 2017 at 12:10

CommunityBot

11 silver badge

answered Nov 30, 2016 at 5:54

Amrinder Singh

821 gold badge2 silver badges10 bronze badges

1 Comment

KC Wong Over a year ago

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

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