When I close a BufferedInputStream, is the underlying InputStream also closed?

From the source code of BufferedInputStream :

public void close() throws IOException {
    byte[] buffer;
    while ( (buffer = buf) != null) {
        if (bufUpdater.compareAndSet(this, buffer, null)) {
            InputStream input = in;
            in = null;
            if (input != null)
                input.close();
            return;
        }
        // Else retry in case a new buf was CASed in fill()
    }
}

So the answer would be : YES

BufferedInputStream doesn't hold any system resources itself; it simply wraps around an InputStream which holds those resources. Therefore the BufferedInputStream forwards the close operation onto the wrapped InputStream which will then release its resources.