This is the implementation of map() method:When I call map() like this, what is the type of T and U? What is the type of wildcard (?)? It is very confusing.
As I understand, generics is an elegant solution to resolve issues with extra boxing/unboxing procedures which occur within generic collections like List. But I cannot understand how generics can fix problems with using interfaces within a generic function. In other words, if I want to pass a value instance which...
I have the following code:It compiles, runs and obviously I get an System.InvalidCastException. Why does the compiler not complain? MyClass is a simple bean, no extensions.
I have an enum with descriptions as String. This is the enum.Now, if I need the data for A, I'd just do
I have this simple interface:I see that this is always an instance of Node<E> (by definition). But I can't imagine a case where this is not an instance of E... Since E extends Node<E>, shouldn't Node<E> also be equivalent to E by definition??
I'm trying to pass a 2-dimensional array, int arr.I cannot use func1(arr) , but I can use func2(arr)
My understanding is generic types are invariant, so if we have B as a subtype of A, then List<B> has no relationship with List<A>. So casting won't work on List<A> and List<B>.
From my prerequisites, generic types are invariant, so I can say if we have B subtype of A, then List<B> has no relationship with List<A>. So casting won't work on List<A> and List<B>
I am trying to create a method in an interface with a generic return type but I fail to cast the generic to a specific type/class. But if I put the generic on the interface instead of the method I am able to do the casting.
I am using java 8.I recently came across this:This does not throw a java.lang.ClassCastException. Why is that?