casting an object to an interface benifits : If i have an object with like 50 methods . 
And on another class , i needed to store this object and use 2 of these 50 methods .

Does creating an interface with 2 methods and casting the original methods to it saves space ?

I mean in this case , will the interface reference contains 50 methods , or will it delete all the methods that are not in the interface and use the needed ones ?

The same with abstract classes . 

I am a little confused about the refrences , if i used a reference of a small interface with 2 methods to store a class with 50 methods , does that have any benifits .

Here is why i am asking , i see this example in android studio many times : 

    @Override
        public void onAttach(Context context) {
            super.onAttach(context);
    
            try {
                CreatedInterface object = (CreatedInterface) context;
    
            }
            catch (ClassCastException e){
                Log.i(TAG , "on attach failed ");
            }
        }

They always don't store the entire context refrence , they create an interface with a subset of it .