This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
It really is false. that is about the String class in Java. String objects are IMMUTABLE. that is:
s.concat(s2) creates a new object whose value is equal to s+s2, but as this new object is not referenced by any variable, it is unreachable. On the other hand, the original object referenced by 's' remains unchanged.