how to create instance of a class to be known at runtime?

Question

1. How can we we create an object of a class with parametrized constructor,and the name of the class would be given to us at the run time as command line argument.

Answer 1

1- To create a class instance at runtime using reflection :

Class classToInstantiate = Class.forName(className);
Constructor theClassInstructor = classToInstantiate.getDeclaredConstructor();
Object instance = theClassInstructor.newInstance();

With:

• parametersClasses array of the classes of the constructor parameters, for example if the constructor uses a String and an Integer parameter you write : getDeclaredConstructor(new Class[]{String.class,Integer.class});
• parameters are the actual values of the parameters to use when instantiating.