When using Java programs to write files, remember to flush ()

Using Java programs to write files to disk encountered the problem: The file is not fully written.

If the content (Stringbuffer/stringbuilder) has 100W characters, but the Java program writes to the file but not 100W, some characters are missing.

The code is roughly like this:

1     Private void throws Exception {2         New File ("File_path"); 3         NULL ; 4         New OutputStreamWriter (new  fileoutputstream (file)); 5 6         Osw.write ("A HUGE ... HUGE STRING "); 7     }

The file is generated. The content is not correct and only some characters are written.

I even wonder if Stringbuffer/stringbuilder also has a length limit? Because the characters are as many as the files are written each time.

Now think about it, it is a pattern Tucson broken ah.

Later, after the reminder, you flush it?

Then suddenly dawned.

The correct code should look like this:

1  　　 Private voidWriteToDisk2 () {2File File =NewFile ("File_path");3OutputStreamWriter OSW =NULL;4         Try {5OSW =NewOutputStreamWriter (Newfileoutputstream (file));6 7Osw.write ("A HUGE ... HUGE STRING ");8 9}Catch(FileNotFoundException e) {Ten e.printstacktrace (); One}Catch(IOException e) { A e.printstacktrace (); -}finally { -             Try {  osw.flush ();  osw.close ();  -}Catch(IOException e) { - e.printstacktrace (); +             } -         } +}

Without flush, direct close is OK.

But the official Java documentation reminds you: Flush before close.

Closes the stream, flushing it first. Once The stream has been closed, further write () or flush () invocations'll cause an ioexception to be thrown. Closing a previously closed stream has no effect.

I shouldn't have made such a mistake.

School teachers are taught, open the flow must remember to close .

0 teacher, I'm sorry, I was wrong.

Because it is only a small test program, not so standard write try/catch, straight throw away.

Stop. Don't make excuses for yourself.

The small program also has its own rules/specifications, to be observed.

When using Java programs to write files, remember to flush ()