Q:

Java - Redirecting system.out.println to a JLabel

I want to redirect a sytem.out.println to a JLabel in another class.
I have 2 classes, NextPage and Mctrainer.
NextPage is basically just a Jframe (The gui for my project), and I have created a Jlabel in Nextpage using this code;
public class NextPage extends JFrame {

    JLabel label1; 

    NextPage() {
        label1 = new JLabel();
        label1.setText("welcome");
        getContentPane().add(label1);

This is the code for Mctrainer:
public class Mctrainer {

    JLabel label1;

    Mctrainer() {
        HttpClient client2 = new DefaultHttpClient();
        HttpPost post = new HttpPost("http://oo.hive.no/vlnch");
        HttpProtocolParams.setUserAgent(client2.getParams(),"android");
        try {
            List <NameValuePair> nvp = new ArrayList <NameValuePair>();
            nvp.add(new BasicNameValuePair("username", "test"));
            nvp.add(new BasicNameValuePair("password", "test"));
            nvp.add(new BasicNameValuePair("request", "login"));
            nvp.add(new BasicNameValuePair("request", "mctrainer"));
            post.setEntity(new UrlEncodedFormEntity(nvp));

            HttpContext httpContext = new BasicHttpContext();

            HttpResponse response1 = client2.execute(post, httpContext);
            BufferedReader rd = new BufferedReader(new InputStreamReader(response1.getEntity().getContent()));
            String line = "";
            while ((line = rd.readLine()) != null) {
                System.out.println(line);
            } 
        } 
        catch (IOException e) {
            e.printStackTrace();
        }
    }

Mctrainer basically just prints out JSON data from a server using system.out.println. 
I want to redirect it to show up in the JLabel in my GUI (NextPage) instead of console.
Any suggestions on how to do this?

A:

You need only to change the default output...
Check out System.setOut(printStream)
public static void main(String[] args) throws UnsupportedEncodingException
{
    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    System.setOut(new PrintStream(bos));
    System.out.println("outputing an example");
    JOptionPane.showMessageDialog(null, "Captured: " + bos.toString("UTF-8"));
}

Also, your question is pretty similar to this other one, so I could adapt this accepted answer to work with JLabel
public static void main(String[] args) throws UnsupportedEncodingException
{
    CapturePane capturePane = new CapturePane();
    System.setOut(new PrintStream(new StreamCapturer("STDOUT", capturePane, System.out)));

    System.out.println("Output test");

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new BorderLayout());
    frame.add(capturePane);
    frame.setSize(200, 200);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);

    System.out.println("More output test");
}

public static class CapturePane extends JPanel implements Consumer {

    private JLabel output;

    public CapturePane() {
        setLayout(new BorderLayout());
        output = new JLabel("<html>");
        add(new JScrollPane(output));
    }

    @Override
    public void appendText(final String text) {
        if (EventQueue.isDispatchThread()) {
            output.setText(output.getText() + text + "<br>");
        } else {

            EventQueue.invokeLater(new Runnable() {
                @Override
                public void run() {
                    appendText(text);
                }
            });

        }
    }        
}

public interface Consumer {        
    public void appendText(String text);        
}

public static class StreamCapturer extends OutputStream {

    private StringBuilder buffer;
    private String prefix;
    private Consumer consumer;
    private PrintStream old;

    public StreamCapturer(String prefix, Consumer consumer, PrintStream old) {
        this.prefix = prefix;
        buffer = new StringBuilder(128);
        buffer.append("[").append(prefix).append("] ");
        this.old = old;
        this.consumer = consumer;
    }

    @Override
    public void write(int b) throws IOException {
        char c = (char) b;
        String value = Character.toString(c);
        buffer.append(value);
        if (value.equals("\n")) {
            consumer.appendText(buffer.toString());
            buffer.delete(0, buffer.length());
            buffer.append("[").append(prefix).append("] ");
        }
        old.print(c);
    }        
}

