This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Somewhere in your Java installation folder you will find a file called src.zip. Unzip that, then navigate to its "java" folder, then its "lang" folder. You will notice the folder structure follows the package name structure.
subject: where to see the source code for java.lang.String