public void setKeepAlive(boolean on) throws SocketException { if (impl == null) throw new SocketException("Not connected");
public void setKeepAlive(boolean on) throws SocketException { if (isClosed()) throw new SocketException("socket is closed");
	public void setKeepAlive(boolean on) throws SocketException {		if (impl == null)			throw new SocketException("Not connected");		impl.setOption(SocketOptions.SO_KEEPALIVE, new Boolean(on));	}