The question was arisen about an array of objects when it's more in the source code than it's required. For example, I have Button objects like this(not initialized yet):
Button[] buttons = new Button[99]
So the question is that if I create and initialize say for instance only 10 of them, will there be any additional memory consumption because of the 99 array of buttons?
The answer is: Yes, some additional space will be wasted - but it's not very much.
Assuming a Button is a reference type, the space used for the array is numberOfElements * size of a reference when you first create the array without creating any Button objects.
The size of a reference is, of course, 32 bits when running as a 32-bit process and 64 bits when running as a 64-bit process.
So for your example with 10 buttons in an array sized for 99, the total space taken for a 64-bit process would be:
Size of the array + 10 * (size of a Button)
Where the size of the array would be 99 * size of a reference, or 99 * 8 (bytes).
(The 8 bytes in that calculation is because 64 bits == 8 bytes)
The new operator automatically initializes the elements of an array to their default value, which, for example, is zero for all numeric types and null for all reference types. - this tells you that all the elements are initialised to a null reference, from which you can tell the size of the array will be #elements * sizeof(reference)
Buttonis a value or reference type