closing nested streams [duplicate]

问题:

This question already has answers here:

Closed 8 years ago.

Possible Duplicate:
Best way to close nested streams in Java?

How we close nested streams? Closing all of them? If yes what is the order?

FileOutputStream out = new FileOutputStream("data.txt", true);
PrintWriter pout = new PrintWriter(out);

/* do some I/O */

pout.close();
out.close();

or closing the the out most stream will close all of them.

pout.close(); // Is this enough?

回答1:

When closing chained streams, you only need to close the outermost stream. Any errors will be propagated up the chain and be caught.

Take a look at here. Probably this question has been asked before.

回答2:

Always close resources with a finally block:

acquire();
try {
    use();
} finally {
    release();
}

Your only resource here is the FileOutputStream, so it's the only one which really needs to be closed. If the PrintWriter constructor was to throw, you really should release the FileOutputStream anyway, which precludes just closing the PrintWriter.

Note, you really do want to flush the PrintWriter. This only needs to be done in the non-exception case so doesn't need a finally.