A little trouble with Lists....

Hi guys and ladies, i´ve got a little problem...i am creating a simple text game...i have a class Thing, then i have class Room(rooms in game, example office, coridor,...)...in this class i have ArrayList filled by objects of Thing class....and now i create class Inventory and there is another ArrayList and now i dont know how to take things from firs list and put them to second(from rooms to inventory)....does anybody know how to solve this??

maybe you could look at java API because there are methods get and add. do you want to move everything from array 1 to array 2? because if it is just some things maybe you could use something along the lines of array2.add(array1.get())