function which return the object of input index

Question

I have a function like

public object getObj(int index,object[] a)
{
  if(index>a.size)
       //what to return??
  else
    return a[index-1];
 }

What should I return if the index is bigger than size? I don't want to return null since null can be an object and I want to be able to distinguish between the cases that index is bigger than size and the object is null itself. How should I use java error handler classes?

Answer 1

When someone supplies a negative index or an index that is out of bounds, it is definitely a programming error. Programming errors are signaled in Java by throwing unchecked exceptions (i.e. ones deriving from RuntimeException). In this specific case, you should throw IndexOutOfBoundsException.