For example I have an Observable and 2 various obeserver. I need to pass two different type of object to them. How can I use Observer-Observable design pattern in this context? Or Do I need to go for some other ways? If so what's it?
In my opinion it's best not to use Observable and Observer at all, because Observable should have been an interface, and they are not strongly typed.
Instead, write a listener interface for each event that you want to listen for. The class that you want to observe should provide methods that can add and remove listeners for a specific event.
Maybe you can explain a bit more what the different types of objects are that you want to pass around?