Java generic member initialization

Question

Suppose I have a Java class parameterized on that contains a private T _member. I want to write a default constructor (no arguments), that somehow initializes my T _member to some known, type T specific value (like -1 for Integer, Float.MAX_VALUE for Float...). Is that possible? I tried new T(), but the compiler doesn't like that. Or do I do nothing, and the default constructor is guaranteed to be called for me?

Answer 1

Because of type erasure, at runtime "there is no T".

The way around it is to pass an instance of Class<T> into the constructor, like this:

public class MyClass<T> {

    T _member;

    public MyClass(Class<T> clazz) {
        _member = clazz.newInstance(); // catch or throw exceptions etc
    }

}

BTW, this is a very common code pattern to solve the issue of "doing something with T"