Question

I am using the getConstructors() method to pull the class’s contructors. The class is in an abstract superclass reference, and I won’t know which subclass is being called until the user decides. Here’s what I have so far.

Weapon stickCopy = stick;
System.out.println(stick);
System.out.println(stickCopy);

Class <? extends Weapon> myClass = stick.getClass( );

System.out.println(myClass.getSimpleName( ));

Constructor<?>[] construct = myClass.getConstructors( );

for(Constructor<?> constructor: construct)
{
    System.out.println(constructor);
}

try
{
    stickCopy = (Weapon) construct[2].newInstance((stick));
}
catch (Exception e)
{
    // TODO Auto-generated catch block
    e.printStackTrace();
}

System.out.println(stick);
System.out.println(stickCopy);

The Stick class is a subclass of the abstract Weapon class. I am trying to figure out the code for a deep copy from a Weapon reference, stored in a player object. Since Weapon is abstract, I can’t call a copy constructor from it. In my Stick class, the copy constructor is the third constructor, and so I hard-coded 2 into the construct array in the try statement. If I change the stick class’s constructors by, say, adding a new constructor in front of the copy constructor or reordering them, how can I find the position of the copy constructor at run-time?

Also, I have never used Generics before, so, if I am not following what are generally considered good programming practices, please correct me.

Answer 1

If you use the version of getConstructor that takes arguments you can specify the constructor you want by its argument types. Presumably you’ll want to pass either Stick.class or Weapon.class in:

Constructor constructor = myClass.getConstructor(myClass);