code factory method

Question

I want to create something I can only describe as a "code factory method".

To avoid code repetition, I want to create a method which contains the code to be executed, but with "placeholders" where the types are supposed to go. The method would of course take these types as parameters and place each one in its appropriate spot. For example:

void factory(placeholder1, placeholder2){  
  ArrayList<placeholder1> List = new ArrayList<placeholder1>;  
  Placeholder2 variable;  
}  
factory(String, Integer);

would yield:

ArrayList<String> List = new ArrayList<String>;  
Integer variable;

any ideas how I would go about this?

Your help is much appreciated.

EDIT: Thank you for all the feedback. I was going with the generic approach and it was working for awhile until I came across what I believe someone mentioned earlier. I want to use one of the methods within one of the generic objects like:

Integer variable = new Integer();
variable.isInteger();

It doesn't appear that I will be able to do this using generics. Is there possibly a workaround to this?

Answer 1

Here's how it would look:

<placeholder1, placeholder2> void factory(){  
  ArrayList<placeholder1> List = new ArrayList<placeholder1>;  
  placeholder2 variable;  
}  
this.<String, Integer> factory();

But I agree with matt that you should read up on generics. Also, be cautious of type-erasure as this might not do everything you expect.

Answer 2

Rather than simply adopting generics, it looks like you want some sort of macro facility. Java doesn't have that. For example, to expand your example a bit, you couldn't do anything like this:

factory(String, Integer);
List.get(variable);