Is String Concatenation memory efficient?

Question

Which is more memory efficient:

Concatenating two Strings, or just having one String with both values in it?

My code below gives an example of both cases.

Thank you in advance.

https://code.sololearn.com/cdqv4F5k2GWF/?ref=app

Answer 1

Of course creating less variables is more memory efficient so if you can have one string don't create two of them.

Answer 2

Ok, then what about

String x = “HelloWorld”;
String y = “Hello” + “World”;

Which is more efficient. x or y?

Answer 3

this is the same