This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
You are creating a new String object"hellobfgkjdf" and substituting that for the original String. The two Strings "hello" and "bfgkjdf" still exist, but are unreachable because their references are changed.