java - Closing a nested stream closes its parent streams too?

Question

OutputStream fos;
OutputStream bos;
OutputStream zos;
try {
    fos = new FileOutputStream(anyFile);
    bos = new BufferedOutputStream(fos);
    zos = new ZipOutputStream(bos);
} finally {
    if (zos != null) {
        zos.close(); // + exception handling
    }
}

Does closing zos automatically closes bos and fos too, or do I need to close them manually?

Answer 1

Yes, it does. Its Javadoc says:

Closes the ZIP output stream as well as the stream being filtered.

Also, the Javadoc for BufferedOutputStream says:

Closes this output stream and releases any system resources associated with the stream.

The close method of FilterOutputStream calls its flush method, and then calls the close method of its underlying output stream.

So when you close your ZipOutputStream, it will close your BufferedOutputStream, which will in turn close your FileOutputStream.