Personally: I've always found this to be the way to go.
Code:
value = leftStick.getRawAxis(1);
getAxis returns a object of type Axis. getRawAxis returns the value of the axis. Multiply by -1 accordingly.
note that the 1 in my code is the axis number. Usually, joysticks return the "x" axis as axis 0, the "y" axis as axis 1, and additional analog axes (thumb wheels, xbox controller triggers, etc) as 2, 3, 4, etc.