Close and BufferWriter

[Berlin Brown]

This is basic java, and I have an idea, but without looking at the java
code, I cant get an 100% understanding.

File _file = new File("somefilename");
FileWriter fileWriter = null;
BufferedWriter outputFile = null

fileWriter = new FileWriter(_file);
outputFile = new BufferedWriter(fileWriter);
PrintWriter out = new PrintWriter(outputFile);

outputFile.close(); // ???
out.close(); // ???


In this close what would physically close the file.
outputFile.close() ...which is the BufferedWriter or
out.close();

 

[Michael Borgwardt]

This is basic java, and I have an idea, but without looking at the java
code, I cant get an 100% understanding.

File _file = new File("somefilename");
FileWriter fileWriter = null;
BufferedWriter outputFile = null

fileWriter = new FileWriter(_file);
outputFile = new BufferedWriter(fileWriter);
PrintWriter out = new PrintWriter(outputFile);

outputFile.close(); // ???
out.close(); // ???


In this close what would physically close the file.
outputFile.close() ...which is the BufferedWriter or
out.close();

Both, becaause all stream, writer and reader classes call the
underlying stream/writer/reader's close() in their close()
method. It is therefore sufficient (and advisable) to call the
outermost stream/writer/reader's close().

 

[Mike Schilling]

Both, becaause all stream, writer and reader classes call the
underlying stream/writer/reader's close() in their close()
method. It is therefore sufficient (and advisable) to call the
outermost stream/writer/reader's close().

Conversely, if you're done with an output filter but don't want to close the
underlying stream, just flush() the filter. (There's no similar solution
with input filters, since there's no general way to push the stuff buffered
in the filter back onto the input stream.)

 

[Filip Larsen]

Berlin Brown wrote

File _file = new File("somefilename");
FileWriter fileWriter = null;
BufferedWriter outputFile = null

fileWriter = new FileWriter(_file);
outputFile = new BufferedWriter(fileWriter);
PrintWriter out = new PrintWriter(outputFile);

outputFile.close(); // ???
out.close(); // ???

In this close what would physically close the file.
outputFile.close() ...which is the BufferedWriter or
out.close();

The typically use is to close the outermost Writer in the chain, which
in your case is the BufferedWriter. It will then flush its buffers and
propagate close to the next Writer in the chain. There is really no need
to close the FileWriter explicitely, but if you do you should do it
*after* you have closed or at least flushed the BufferedWriter.


Regards,

 

[John C. Bollinger]

Berlin Brown wrote

The typically use is to close the outermost Writer in the chain, which
in your case is the BufferedWriter.

Look a bit closer: in his case the outermost Writer is the PrintWriter.
Just pointing it out in hopes of avoiding confusion.


John Bollinger
(e-mail address removed)