flush in java.io.FileWriter

Question

I have a question in my mind that, while writing into the file, before closing is done, should we include flush()??. If so what it will do exactly? dont streams auto flush??

Answer 1

To answer your question as to what flush actually does, it makes sure that anything you have written to the stream - a file in your case - does actually get written to the file there and then.

Java can perform buffering which means that it will hold onto data written in memory until it has a certain amount, and then write it all to the file in one go which is more efficient. The downside of this is that the file is not necessarily up-to-date at any given time. Flush is a way of saying "make the file up-to-date.

Close calls flush first to ensure that after closing the file has what you would expect to see in it, hence as others have pointed out, no need to flush before closing.