public class A<B> {
public func() {
B b = new B();
}
}
I get this error hint from Netbeans:
unexpected type
required: class
found: type parameter B
where Bis a type-variable:
B extends Object declared in class A
How can I new a object of class B?
B in A<B> is just a type parameter. You cannot create an instantiate a parameter. You can only create an instance of actual type.
But you can declare the method to take that instance as an argument public func(B b).
I recommend you to read the tutorial on generics.
public class MyComp implements Comparator<MyObject>, you can always instantiate MyObject in compare method.
new T().
Due to type erasure you cannot make it like that. Take a look at the following answer https://stackoverflow.com/a/6810709/860294
Java uses type erasure. it doesnt know the class of B, and so it doesnt know whether whatever class B ends up being at run time will have a constructor with that set of arguments.
The reason for this is that B can be either an interface or a class (even Abstract one). So, new B() will not be valid in case of Interface or Abstract Class. Hence, it is not allowed.
