Actual size in bytes occupied by an array of x datatype in java?

Question

How can "size in bytes" of a array of some datatype be determined?

What makes me ask this is a question from this icse board question paper.

The question is as follows:

And the accepted answers by the board are (space occupied by one of those data types*no of elements in the array)

For example , one int array of 10 objects is said to take 4*10=40Bytes

But my question is, wouldn't the array have to store it's length and indexes somehow(increasing it's size on memory), or am I misunderstanding the question?

Answer 1

Your understanding is indeed correct. The official answer adopts a simplistic view of how arrays are stored.

There is a fixed cost associated with every object. Additionally, arrays need to keep track of their size and possibly other things.

The answer also ignores issues such as padding, alignment, etc.