I have FinanceRequests and CommisionTransactions in my domain. If I have a list of FinanceRequests each FinanceRequest could contain multiple CommisionTransactions that need to be clawed back. Dont worry how exactly that is done. The class below (very bottom) makes me feel all fuzzy and warm since its succint…
Tag: generics
Generic type as parameter in Java Method
Do you think it is possible to create something similar to this? Answer Yes, you can. Usage example:
Java override abstract generic method
I have the following code However I don’t know how to do this, as I cannot override doEventStuff with something specific. Does anyone know how to do this? Answer It’s not really clear what you’re trying to do, but perhaps you just need to make Event itself generic:
Getting the class of the components of an array
If I have how can I get T.class from array? If I do array.getClass() that gets me T[].class instead. Answer Component Type Use this: Returns the Class representing the component type of an array. If this class does not represent an array class this method returns null. Reference: Class.getComponentType() Safe…
Why shouldn’t Java enum literals be able to have generic type parameters?
Java enums are great. So are generics. Of course we all know the limitations of the latter because of type erasure. But there is one thing I don’t understand, Why can’t I create an enum like this: This generic type parameter <T> in turn could then be useful in various places. Imagine a gener…
Why doesn’t this generic cast fail?
I’d expect this code to throw a ClassCastException: But it doesn’t. Casting String to T doesn’t fail, until I use the returned object somehow, like: Background: I created a Class which uses JAXB to unmarshal an XML file. It looks like this: Depending on whether the root-Element is an anonymo…
Java generics super keyword
I went through these topics Generics..? Super T Bounding generics with ‘super’ keyword However, I still seem to be kind of lost with super keyword: When we declare a collection like that: shouldn’t it be the opposite – we have a list that contains some objects (of unknown type) which a…
How to cast a list of inheriting objects to a collection of objects in Java?
I’ve a collection type: And I’ve a list in my object: Where B is extending A But I can’t do the following: I can’t understand why since Collection is implemented by List. Answer Let’s assume for a moment you could do what you describe: The method call collecA.add(new A()) appears…
java generics covariance
I am having trouble understanding the following article: http://www.ibm.com/developerworks/java/library/j-jtp01255.html Under, Generics are not covariant the author states, Because ln is a List, adding a Float to it seems perfectly legal. But if ln were aliased with li, then it would break the type-safety pro…
Get generic type of java.util.List
I have; List stringList = new ArrayList(); List integerList = new ArrayList(); Is there a (easy) way to retrieve the generic type of the …