What is the appropriate way to initialize an implemented class of an interface (determined by some logic)
Example
IAnaimal is an interface
Cat -> IAnimal
Dog -> IAnimal
Cow -> IAnimal
int x = in.nextInt();
IAnimal animal = null;
if(x==1)
animal = new Dog();
else if(x==2)
animal = new Cat();
else
animal = new Cow();
animal.destroyManKind();
Is this the correct approach? Is there a 'more' professional way of doing this?
I would have a cleaner way of reading the name instead of 1, 2 and 3 but you can use a switch in this case.
int choice = in.nextInt();
switch(choice) {
case 1: animal = new Dog(); break;
case 2: animal = new Cat(); break;
default: animal = new Cow(); break;
}
or using a string switch
String choice = in.next();
switch(choice.toLowerCase()) {
case "dog": animal = new Dog(); break;
case "cat": animal = new Cat(); break;
case "cow": animal = new Cow(); break;
default: // error
}
There is nothing wrong in your way of doing. You can also look in to Factory design pattern.
switch (x){
case 1:
animal = new Dog();
break;
case 2:
animal = new Cat();
break;
default
animal = new Cow();
}
Are you sure that Cow is a useful default?
Assuming they have a common super class Animal, it could have a static builder method that takes an int, you could do this
IAnimal animal = Animal.build(x);
where
public class Animal{
public static IAnimal build(int x){
if(x==1) return new Dog();
else if(x==2) return new Cat();
return new Cow();
}}
I would prefer a animal array
IAnimal animal = null;
IAnimal [] animals ={null,new Dog(),new Cat(),new Cow()};
animal = animals[x]
in.next()came from? You might use aswitch instead ofif-else of -else`classor direct-type.Dog d = new Dog();