Casting of Object[] to Animal[] fails

[Alexander Curvers]

Hi

Casting of Object[] to Animal[] fails while the Object[] array contains only Animal objects
when i use a for loop to add each Animal out of the Object[] array to the Animal[] array it works.. but like stated just trying to cast it in one line of code (Animal[]) fails
why is that?

[Kevin Workman]

Can you post the code you're attempting? It seems to work fine for me.

[Matthew Brown]

How are you creating the Object[]? Because only putting Animals into an Object[] is not enough to make it an Animal[]. You need to have actually created an Animal[] in the first place.

[Alexander Curvers]

thank you both for your replies

Matthew Brown wrote:How are you creating the Object[]? Because only putting Animals into an Object[] is not enough to make it an Animal[]. You need to have actually created an Animal[] in the first place.

with [List].toArray() it makes a Object[] so its clear that is the problem maybe there is a better way to convert the list to an array? so it can be cast or doesnt need to be casted

   
List<Animal> result = new ArrayList<Animal>();
			
			for (....) {
				result.add(new Animal());
			}

			return result.toArray();
 

[Matthew Brown]

Ah, thought it might be that! There's a trick. You need the version of toArray that takes an argument.

<T> T[] toArray(T[] a)
Returns an array containing all of the elements in this list in proper sequence (from first to last element); the runtime type of the returned array is that of the specified array.

So if you try:

return result.toArray(new Animal[0]);

it'll return an Animal[].

[Alexander Curvers]

Ah thanks Matthew! thats what i needed

[Rob Spoor]

Slightly better, because it creates only one array (with elements) instead of two (one empty one, one with elements):

return result.toArray(new Animal[result.size()]);