Standard Place for an Empty String Array in the JDK

Question

Hi is there a standard place for accessing empty array constants in the JDK > 1.5.

When I want to do a conversion from a String Collection (e.g. ArrayList)to a String Array I find myself using my own which is defined in my own Constants class:

public static final String[] EMPTY_STRING_ARRAY = new String[0];

And then in my client code something like:

String[] retVal = myStringList.toArray(Constants.EMPTY_STRING_ARRAY);
return retVal;

I was wondering if this is the "idiomatic" way of doing it or if I'm missing something I get the impression from the brief search I did that this kind of thing is prevalent in many people's code.

Any ideas, answers, comment (aside from that I shouldn't really use String Arrays) greatly appreciated,

Cheers Simon

Answer 1

There are no array definitions like that in the JDK anywhere. The only two standard ways of doing it in the JDK are that which you list or

String ret[] = new String[myStringList.size()];
myStringList.toArray(ret);
return ret;

Answer 2

I would recommend the following code improvement :

String[] retval = myStringList.toArray(new String[myStringList.size()]);

This way, the toArray method uses the provided, appropriately-sized array as a container, instead of creating a new one behind the scenes. From the ArrayList javadoc :

If the list fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this list.