small collections VS large arrays

[fipi]

Hi, I was just wondering if in some cases collections can use less memory than arrays. Collections (like an ArrayList) are simply objects linked to each other with no maximum size, right? But arrays allocate memory for their contents when they are created, right? (Correct me if I'm wrong, please.) So, for example, would an ArrayList with 50 objects use less memory than an array with a length of 1000 but only containing 50 objects?