Android: How do I call a method which is existing in other API Level?

Question

I have application using Android 2.1 which utilize LocationManager to get the altitude. But now, I need to obtain the altitude using SensorManager which requires API Level 9 (2.3).

How can I put the SensorManager.getAltitude(float, float) in my 2.1 android application by putting a condition and calling it by a function name (possible in normal Java)?

Thank you in advance

UPDATE 1 If you have noticed that my application need to be compiled using Android 2.1. That's why I'm looking for a way to call the function by name or in any other way that can be compiled.