Java Programming

Hi,

I want to use log4j to log data into memory .I'm not sure if WriterAppender is the one to use for this purpose ?

here is the description of the problem :
at all times log to memory using the logger.logger should be writing to a memory stream (memory writes are cheap in performance)
if user wants a manual log (push button) then write to disk (performance expensive)
if an exception occurs most likely i will still have access to the memory location using the static singleton

how can i do that with log4j library ?

thanks