Question

I have a collection of objects which are all the same object type. Within that type there is an attribute that I want to access – in this case it’s to add it to a comma separated list:

String sep = ", ";
List<Item> items = db.findItems();

for (Item item : items) 
{
    result.append(item.getDescription() + sep);
} //for

return result.substring(0, results.length - sep.length());

It would be nice if I could just directly access that attribute from all the objects in the collections so that I could call Google Guava’s Joiner function:

return Joiner.on(", ").join(/*Description attribute collection here*/);

The kind of structure I’m thinking of is like a 2D array where each column represents an attribute and each row represents an object and so I want to be able to call either a specific row which returns the object or a specific column (attribute) that returns a collection of the attributes from all objects.

Does Java or a good third party have a data structure like this or would I need to create my own?

Cheers,

Alexei Blue.

Answer 1

Why don’t you use Google’s Guava to the fullest then?

Joiner.on(",").join(Collections2.transform(items, new Function<Item, String>() {
    public String apply(Item input) {
        return item.getDescription();
    }
}));