How to compile against multiple libraries w/ different API's

Question

I am trying to write code that will run with 2 different versions of a Java library. The API is different between those 2 library versions.
For example in library v1.1 I have a method:
myMethod(String x) {...}And in library v1.2 I have a method:
myMethod(String x, String y) {...}In my calling code I have a way to determine what version of the library is present. I want to dynamically choose at runtime which API to call based on this version. Roughly, the code would look like this:
if (version = "1.1")
    myMethod("arg1");            //call 1.1 API
else if (version = "1.2")
    myMethod("arg1","arg2");   //call 1.2 API
  }The problem is that I cannot compile my code with both versions of my library at the same time. The method whose corresponding library is not used to compile always causes an error.
Can someone suggest a design pattern that I can use to get around this? There must be some way to call a different version of myMethod() (with different number of parameters) without exposing it to the compiler.
Thanks.

Answer 1

The problem is that I cannot compile my code with
both versions of my library at the same time. The
method whose corresponding library is not used to
compile always causes an error.
Huh?
You do have two versions of the library right? And you can compile both right?
If so then the problem is the application.
If so.....
- You create a proxy library. It loads the real library dynamically using reflection based on however you determine which is correct.
- You compile the application using the proxy library.
Note that in the above the application is NOT compiled with the two real libraries. The libraries are compiled seperately.