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.
A String is supposed to represent characters, not the full range of the char data type. I would wager that the value you are attempting to set cannot be represented in your default charset so it gets substituted. For further info, read up on java.nio.charset.Charset and look up your local Unicode code chart