Question

Let’s say that I have a function that has the purpose of creating a new instance of any specified class, and then returning it. Perhaps something like this:

public static <T> Class<T> forgeClass(Class<T> classReference) {

    return new classReference.getClass();

}

Usage (with Employee class):

Employee foo = forgeClass(Employee.class); // new Employee instance

How can I achieve this?

Answer 1

The key is to use Class.newInstance;

public static <T> T forge(final Class<T> type)
    throws InstantiationException, IllegalAccessException {
  return type.newInstance();
}

Use as follows…

final Employee employee = forge(Employee.class);

In case you want to use a more complex initialization routine, e.g. Employee(String name), you should use Class.getConstructor, followed by Constructor.newInstance.

final Constructor ctor = Employee.class.getConstructor(String.class);
final Employee employee = ctor.newInstance("Steve");