io - difference between flush and close function in case of filewriter in java

Question

I need to know what is exact difference between flush and close function in Java?

And When the data is dumped into a file during writing of file?

Please provide one example

Answer 1

flush() just makes sure that any buffered data is written to disk (in this case - more generally, flushed through whatever IO channel you're using). You can still write to the stream (or writer) afterwards.

close() flushes the data and indicates that there isn't any more data. It closes any file handles, sockets or whatever. You then can't write to the stream (or writer) any more.

Note that without calls to flush() data can still be written to the IO channel in question - it's just that some data might be buffered.

close() generally calls flush() as well, but it's recently been pointed out to me that in some JDK implementations, any exceptions thrown by flushing as part of closing are swallowed :(