Delta_avi_delta ......unknown source problem...

Question

When i try to put in the lines that you posted on the forum, i manage to compile but when i actually read from the serial port, error occurs....The error is
java.lang.NullPointerException
at java.io.ByteArrayOutputStream.writeto(Unknown source)
at Read.serialEvent(Read.java:99)
import javax.comm.*;
import java.io.*;
import java.util.*;
public class Read implements Runnable, SerialPortEventListener {
     // Attributes for Serial Communication
     static Enumeration portList;
     static CommPortIdentifier portId;
     SerialPort serialPort;
     static OutputStream outputStream;
     InputStream inputStream;
     Thread readThread;
     ByteArrayOutputStream buffer;
     public static void main(String s[])
     portList=CommPortIdentifier.getPortIdentifiers();
     while(portList.hasMoreElements())
          portId=(CommPortIdentifier)portList.nextElement();
          if(portId.getPortType()==CommPortIdentifier.PORT_SERIAL)
               if(portId.getName().equals("COM1"))
                    System.out.println( portId.getName());
                    Read ss=new Read();
          }     // end of while
}          // end of main
public Read()     {
try{
          serialPort=(SerialPort)portId.open("Read", 2000);
catch(PortInUseException e)     {}
     try{
          inputStream=serialPort.getInputStream();
          System.out.println(inputStream);
catch(IOException e)     {}
     try{
          serialPort.addEventListener(this);
catch(Exception e)     {}
          serialPort.notifyOnDataAvailable(true);
     try{
          serialPort.setSerialPortParams(9600,
          SerialPort.DATABITS_8,
          SerialPort.STOPBITS_1,
          SerialPort.PARITY_NONE);
          }catch(UnsupportedCommOperationException e)     {}
          readThread=new Thread(this);
          readThread.start();
     }//end of constructor
     public void run()
          try     {
               Thread.sleep(200);
          }catch(InterruptedException e)     {}
     public void serialEvent(SerialPortEvent event)
     {buffer=new ByteArrayOutputStream();
       int i;
           switch(event.getEventType())
                case SerialPortEvent.BI:
                case SerialPortEvent.OE:
                case SerialPortEvent.FE:
                case SerialPortEvent.PE:
                case SerialPortEvent.CD:
                case SerialPortEvent.CTS:
                case SerialPortEvent.DSR:
                case SerialPortEvent.RI:
                case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
                break;
                case SerialPortEvent.DATA_AVAILABLE:
                byte[]readBuffer=new byte[8];
               try{
                    while((i=inputStream.available())>0)
                         inputStream.read(readBuffer, 0, i);
                         buffer.write(readBuffer, 0, i);
                         buffer.writeTo(outputStream);
                         buffer.reset();
                    }catch(IOException e)     {}
               break;
               }     // end of switch
               try     {
                    inputStream.close();
                    }catch(Exception e5)     {}
     }          // end of serialEvent

Answer 1

Hey I_ws,
glad I could be some help!
Other poster is right, you need some particular outputstream to output to, say you're outputting to a text file, (I can't remember your original post, but other outputs are similar)
you'd do something like:
DataOutputStream out;
//initialise with constructor...
         try{
              out = new DataOutputStream(
                  new FileOutputStream("log.txt"));
         }catch (FileNotFoundException e) {}
// creating a new data output stream to
//write data to the specified underlying FileOutputStream...
//output part:
inputStream.read(readBuffer, 0, i);   
buffer.write(readBuffer, 0, i);
buffer.writeTo(out);
buffer.reset();
[\code]
hope that helps (and hope it runs!)  I'm reading over my pathetic resume to counteract the ego boost of seeing my handle as a thread subject!
take care :)