there must be some logic behind this...

To find out the length of arrays, you use the length field, like: myArr.length.
To find out the length of strings, you use the length method, like: myStr.length().
To find out the length of ArrayLists, you use the size method, like: myArrayList.size().

It seems to me it should just all be consistent, either all length, or all length() or all size(), just something that seems less arbitrary...