Don't use Date; use one of the newer datatypes described here in the Java™ Tutorials.
You can probably alter the formatting with String#format. The Formatter documentation has all the details in.
Where are you closing your reader and writer? If you don't close a writer, the text may remain in its buffer for ever and never appear at its intended destination. Don't call close(); read this Java™ Tutorials section, which tells you what you should do.
What is wrong with your program? We need the full details before we can help.