在具有2个不同类的JTextArea上检索GPS数据

Question

I have aa GPS receptor. I create a class to retrieve all the GPS data on my Eclipse Console. (This is the code of makia42)

public class COM implements Runnable{
 static   Thread myThread=null;
 static   BufferedReader br;
 static   BufferedWriter wr;
 static   InputStreamReader isr;
 static   OutputStreamWriter osw;
 static   java.io.RandomAccessFile port;

    public  COM(){ /**Constructeur*/
          myThread=new Thread(this);
    }

    public void start(){
        try {
           port=new java.io.RandomAccessFile("COM3","rwd");
           port.writeBytes("\r\n");
           port.writeBytes("c,31,0,0,5\r\n");
           port.writeBytes("T,1000,1\r\n");
        }
        catch (Exception e) {
        System.out.println("start "+e.toString());
        }
        myThread.start();
    }


    public void run() {
          System.out.println("lecture COM...");
          for(;;){
              String st = null;
            try {
                st=port.readLine();
            } catch (IOException e) {System.out.println(e.getMessage());}
                        System.out.println(st);
          }
     }
    public static void main(String[] args) {

              COM temp= new COM();
              temp.start();
    }
}

I have another class which is a frame containing a button and a JTextArea. This class is in communication with my first class COM.

When i click the button, COM is starting and show me the data in my Eclipse Console. But now, I'd like to show it on my JTextArea.

How can I do it ?

Best regards,

Tofuw

Answer 1

Take a moment to read about this pattern . Make the Thread a Subject . Before starting register the instance of the class that contains the JTextArea as the Observer with the instance of the Thread . At the run() instead of printing on the console, use the notify(String) ;

public void run() {
      System.out.println("lecture COM...");
      for(;;){
          String st = null;
        try {
            st=port.readLine();
        } catch (IOException e) {System.out.println(e.getMessage());}
                    System.out.println(st);
      }
}

Change to

public void run() {
      System.out.println("lecture COM...");
      for(;;){
          String st = null;
        try {
            st=port.readLine();
        } catch (IOException e) {System.out.println(e.getMessage());}
                   notifyObservers(st); //Pass the data to the observers.
      }
}

EDIT: I suppose you can rewrite the Thread to a simple class. It will render the program unresponsive while it reads, that's why you have a Thread . I suppose you can implement a cleaner way using Future<String>

public class GpsReader {
    public class GenericGPSException extends Exception {

        public GenericGPSException(String message, Throwable cause) {
            super(message, cause);
        }
    }

    public static void main(String[] args) {

        // Example of usage

        GpsReader gpsReader = new GpsReader();

        String messageFromDevice;
        try {
            // Try read it
            messageFromDevice = gpsReader.getCoordinate();
        } catch (GenericGPSException e) {
            // Error, what does it says?
            messageFromDevice = e.getMessage();
        }

        JTextArea mockArea = new JTextArea();
        // Show to user anything that comes to it.
        mockArea.setText(messageFromDevice);

    }

    private boolean isReady;

    private RandomAccessFile port;

    public GpsReader() {
    }

    public String getCoordinate() throws GenericGPSException {

        if (!isReady) {
            try {
                port = new RandomAccessFile("COM3", "rwd");
                port.writeBytes("\r\n");
                port.writeBytes("c,31,0,0,5\r\n");
                port.writeBytes("T,1000,1\r\n");
                isReady = true;
            } catch (FileNotFoundException e) {
                throw new GenericGPSException(
                        "Error at starting communication to Device ", e);
            } catch (IOException e) {
                throw new GenericGPSException(
                        "Error at starting communication to Device ", e);
            }

        }

        try {
            return port.readLine();
        } catch (IOException e) {
            throw new GenericGPSException("Error at reading the Device ", e);
        }
    }
}