You can use such trick:
myObject = new ArrayList<Object>(myTempObject);
or use
myObject = (ArrayList<Object>)myTempObject.clone();
You can get some information about clone() method here
But you should remember, that all these ways will give you a copy of your List, not all of its elements. So if you change one of the elements in your copied List, it will also be changed in your original List.