Question

Say I have the following piece of java code

ArrayList<Double> myList = new Double[100];
for (Double x : myList)
    x = randomDouble();

Does this actually modify myList or just the dummy variable?

I realize I should just try this code segment out, but I think this is the sort of thing I should be able to google or search for on this site, and several queries so far have turned up nothing useful.

Answer 1

It doesn’t modify myList. It works by calling myList.iterator(), then (repeatedly) hasNext() and next(), none of which change myList.

Also, Java does not have C++-style references. That means you don’t need to worry (even without looking at the API) about x being a reference that could modify myList.

Finally, that’s invalid syntax. It should be:

ArrayList<Double> myList = new ArrayList<Double>(); 
/* or new ArrayList<Double>(100), but that's only an optimization 
(initial capacity), not the size. */