How do you check if a array is full?

Question

suppose you have a array of hmm numbers.
How would you test if the array is full?

Answer 1

What do you mean with "full"? It depends on your definition. There isn't such a thing as an "empty" array. It's values might be null and depending on your definition that might mean "empty", but it might as well not. Usually if you create an array that's bigger than the amount of storage you need right now (for example to avoid re-allocating it later on) you'll also keep another variable that tells you up to which position you already filled it:
int[] myArray;
int position;
public addInt(int value) {
  if (position >= myArray.length) {
    throw new ArrayFullException();
  myArray[position++]=value;
}