Converting Java Collection of some class to Collection of String

Question

Assume a class (for instance URI) that is convertable to and from a String using the constructor and toString() method.

I have an ArrayList<URI> and I want to copy it to an ArrayList<String>, or the other way around.

Is there a utility function in the Java standard library that will do it? Something like:

java.util.collections.copy(urlArray,stringArray);

I know there are utility libraries that provide that function, but I don't want to add an unnecessary library.

I also know how to write such a function, but it's annoying to read code and find that someone has written functions that already exist in the standard library.

Answer 1

I know you don't want to add additional libraries, but for anyone who finds this from a search engine, in google-collections you might use:

List<String> strings = Lists.transform(uris, Functions.toStringFunction());

one way, and

List<String> uris = Lists.transform(strings, new Function<String, URI>() {
  public URI apply(String from) {
     try {
       return new URI(from);
     } catch (URISyntaxException e) {
       // whatever you need to do here
     }
  }
});

the other.