This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
The Java equivalent of a "function" is an object which implements the Runnable interface, if you don't want the function to return anything. If you want the function to return something of type V, let's say, then you need an object which implements the Callable<V> interface. You can put such objects, like any other objects, into an array or a List or a Map, whichever works better for you.