Java : Char vs String byte size

Question

I was surprised to find that the following code

System.out.println("Character size:"+Character.SIZE/8);
System.out.println("String size:"+"a".getBytes().length);

outputs this:

Character size:2

String size:1

I would assume that a single character string should take up the same (or more ) bytes than a single char.

In particular I am wondering.

If I have a java bean with several fields in it, how its size will increase depending on the nature of the fields (Character, String, Boolean, Vector, etc...) I'm assuming that all java objects have some (probably minimal) footprint, and that one of the smallest of these footprints would be a single character. To test that basic assumption I started with the above code - and the results of the print statements seem counterintuitive.

Any insights into the way java stores/serializes characters vs strings by default would be very helpful.

Answer 1

getBytes() outputs the String with the default encoding (most likely ISO-8859-1) while the internal character char has always 2 bytes. Internally Java uses always char arrays with a 2 byte char, if you want to know more about encoding, read the link by Oded in the question comments.