Why can't we create an object with the "this" keyword in java? [closed]

Question

I've seen places where object creation factories are implemented by having a reference to the class object and having a create method which does this:class.newInstance(), which uses reflection, and might not be efficient compared to calling the default constructor directly.

If java supported something like return new this();, I could implement this in a parent class and that would work as a factory method (and would throw an exception if there is no such constructor as does class.newInstance()).

Why isn't such a thing supported?

PS: My first question in stackOverflow :)

Answer 1

As designed, the this keyword is valid only in the context of an instance. Its type is the type of the class within which it occurs.

From the Java Language Specification:

When used as a primary expression, the keyword this denotes a value that is a reference to the object for which the instance method was invoked (§15.12), or to the object being constructed.

If you want to create a new object using the default constructor, you can call it directly.

 return new MyType();

If you want to create a clone of an object, you may be able to use the Object.clone() method.