Can't get output of button to a byte array

Question

I am trying to get the output values of TestButtonHandler to become byte h[] in the connect method. Of course, when I compile it, the button System.out.println works but I get a null pointer exception at
byte h[] = asciiStream.toByteArray(); Would someone give me a clue as to why there's a disconnect? thx
public class MonitorView2 extends JFrame {
     static SerialPort     serialPort;
     ByteArrayOutputStream      asciiStream;
     public MonitorView2()  {
          super("Monitor View 2");
     JPanel pane = new JPanel();
     setContentPane(pane);
     JButton testButton = new JButton("Test Comm On");
     pane.add(testButton);
     setSize(600, 300);
     setVisible(true);
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     class TestButtonHandler implements ActionListener  {
          public void actionPerformed(ActionEvent e) {
               System.out.println("Test button action works!");
               try
               byte h[] = {33, 48, 48, 66, 67, 78, 49, 13}; //comm on;
               ByteArrayOutputStream asciiStream = new ByteArrayOutputStream();
               ObjectOutputStream oos = new ObjectOutputStream(asciiStream);
               oos.writeObject(h);
               oos.close();
               catch (Exception ex)
                    System.out.println("Exception has been thrown :" + ex);
          testButton.addActionListener( new TestButtonHandler());
     public void connect ( String portName ) throws Exception  {
     String defaultPort = "/dev/ttyS0";
     String                asciiString;
     Charset asciiCharset = Charset.forName("US-ASCII");
     CharsetDecoder decoder = asciiCharset.newDecoder();
     byte h[] = asciiStream.toByteArray();
     //byte h[] = {33, 48, 48, 66, 67, 78, 49, 13}; //comm on
     ByteBuffer asciiBytes = ByteBuffer.wrap(h);
     CharBuffer hChars = null;
     try {
          hChars = decoder.decode(asciiBytes);
     } catch (CharacterCodingException e) {
          System.err.println("Error decoding");
          System.exit(-1);
          System.out.println(hChars);
        CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);
        if ( portIdentifier.isCurrentlyOwned() )
            System.out.println("Error: Port is currently in use");
        else
            CommPort commPort = portIdentifier.open(this.getClass().getName(),2000);
            if ( commPort instanceof SerialPort )
                SerialPort serialPort = (SerialPort) commPort;
                serialPort.setSerialPortParams(4800,SerialPort.DATABITS_8,SerialPort.STOPBITS_1,SerialPort.PARITY_NONE);
                InputStream in = serialPort.getInputStream();
                OutputStream out = serialPort.getOutputStream();
                (new Thread(new SerialReader(in))).start();
                (new Thread(new SerialWriter(out))).start();
          out.write(h);
          out.flush();
            else
                System.out.println("Error: Only serial ports are handled by this example.");
   

Answer 1

ByteArrayOutputStream asciiStream = new ByteArrayOutputStream();By actually using the attreibute instead of declaring and initializing another local variable with the same name:
asciiStream = new ByteArrayOutputStream();