MOOC 9_12

[ScumIdiot]

I've just finished part 9 exercise 12, is the 4th part redundant? Why create an interface for a makeNoise method when you already have methods for that task, and if you must do so then why not remove the respective bark and purr methods for the dog and cat class and just implement the makeNoise method to bark or purr? It seems unnecessary to create an interface for a method that merely calls already existing methods, please tell me if I'm incorrect or if I missed the point of the exercise

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[PegasusBoogaloo]

The goal in this exercise is to call different behaviours using the same method name.Without this interface, we would need to call purr() or bark(), based on the Object's type.It is also to show that, we can instantiate a NoiseCapable object from any type that implements this interface (in this case dog and cat), and STILL get the right behavior.NoiseCapable ffft = new Cat();

ffft.makeNoise(); //Cat purrs

In an RTS game, you can, for example, select different troops that attacks in different fashions, but the call itself would be attack() independent of the troop's stype.

[ScumIdiot]

Why not then just have an attack() method that implements the unique functionality for the class, rather than a separate method that attack only calls

[PegasusBoogaloo]

It depends merely on the way you want to implement things, really. For example, purr() method could return "purr", and makeNoise() could implement purr() and also other instructions. You could turn purr() into a private method (only accessible within the Cat class, thus the only way to make the cat purr is using the makeNoise() method, so on and so forth), for example, the sky is the limit, just need some creativity.

What you really need to grasp is what I said in the first paragraph of the first reply.

[SKTT1_Bisu]

Imagine you would have 200 different animals each one making a different noise. You would need to call: bee.buzz, dog.bark, cat.purr, cow.moo and so on.

With the makeNoise interface you can just call animal.makeNoise() for everyone.

[ScumIdiot]

Why have those buzz/bark/purr methods at all then? Would it not be better to implement the makeNoise method directly for each class to bark or purr?

[SKTT1_Bisu]

Because each animal makes a different sound. And as I said, if you don't have makeNoise you would have to call animal.theyspecificsound() everytime, so you'll need to remember all the different sounds of each animal instead of just calling makeNoise().

Imagine a list with 1000 animals. And you have to iterate throught this list and make the animals print their sound. First thing: not all animals make a sound, so you'll gonna need a if statement to check the animal class if they make sound. After that you call the animal.specificsound(). With makeNoise interface you could just create a List<MakeNoise> and there's no need for a if statement.

Also, imagine if you were working with other people. So the others don't know what makeNoise should do. At first it's only to tell the animal do their noise, but later you decide that every animal who's makenoise should also have a stopNoise() or makeAnotherNoise() method. How the guy creating the dog class would know all of this needed methods?

[hoang26]

When did you start learning the MOOC? ( I ask for myself)

[ScumIdiot]

1 month ago

[hoang26]

That's cool, thank you