CODEWITHSUNDEEP
javagenerics
Abichellam
Abichellam

Reputation: 509

Whether to use generics or not?

I have the following hierarchy of classes

public abstract class MyAbstractClass {

}

public abstract class AbstractClassA extends MyAbstractClass {

}
public class AbstractClassB extends MyAbstractClass {

}
public class ClassA extends AbstractClassA {

}
public class ClassB extends AbstractClassA {

}

I have a converter which should accept instance of a class extending AbstractClassA and should return instance of a class extending AbstractClassB. I have two versions of conversion class one using Generic and the other one is not. Both works fins. But what is the correct way of specifying the signature of the converter?

public class ConverterTwo {
    public AbstractClassB convert(AbstractClassA a) {
}
}

public class ConverterOne {
public <A extends AbstractClassA, B extends AbstractClassB> B convert(A a) {
}
}

Upvotes: 3

Views: 115

Answers (4)

sumanr
sumanr

Reputation: 178

Generics are checked only at compile time and are replaced with the proper types during compilation.

ConverterTwo code will be converted to ConverterOne kind of code during compilation and thus both are equivalent.

Generics are especially useful when you write an API where you do not know what kind of objects the consumer of the API's are going to pass. In your case, if you plan to write a generic adapter.

Classic example of genrics : Collection Interface and the classes that implement it.

Upvotes: 1

Nader Ghanbari
Nader Ghanbari

Reputation: 4300

Both are correct but my suggestion is go with ConverterTwo which is simpler. You can always Generify and make a Generic Interface or Abstract class out of your Converter later.

Upvotes: 0

Prabhat
Prabhat

Reputation: 840

Both are correct ways. It's just that ConverterTwo class has less code in signature as compared to ConverterOne. Also both the syntax AbstractClassA and <A extends AbstractClassA> will behave in same manner in this example.

Upvotes: 0

NimChimpsky
NimChimpsky

Reputation: 47290

Use 1, you have all the type checking you need because the parameters extend an abstract class. And its less code than 2, which always a good thing. But neither would be wrong.

Upvotes: 0

Related Questions