why won't my text print to my JTextArea?

Question

I am calling a method that returns a string (edited text from a webpage) and I want to print that string onto my JTextArea. I know that string I am sending to my JTextArea is correct because it will print correctly to the command line, but will not print to the JTextArea. It must be something I am doing wrong in my adding it to the TextArea. Any help would be appreciated.

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;

public class BrowserPanel extends JPanel {

private JTextField textField;
private String urlText;
private JTextArea textArea;
private BrowserPageReader myModel;
private String pageContent;
private BrowserFrame myFrame;
private String pageTitle;
private String pageBody;



public BrowserPanel(JTextField myTextField, BrowserPageReader model,
        BrowserFrame frame)
{
    myFrame = frame;
    myModel = model;
    textField = myTextField;
    textField.addActionListener(new InputHandler());

    /*JScrollPane areaScrollPane = new JScrollPane(textArea);
    areaScrollPane.setVerticalScrollBarPolicy(
            JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);

    areaScrollPane.setPreferredSize(new Dimension(250,250));*/
    textArea = new JTextArea(20,40);
    textArea.setEditable(false);
    textArea.setWrapStyleWord(true);
    textArea.setLineWrap(true);
    JScrollPane scroll = new JScrollPane(textArea);

    add(scroll);
}

public void paintComponent(Graphics g)
{
    super.paintComponent(g);

}
private class InputHandler implements ActionListener
{
    public void actionPerformed(ActionEvent e)
    {
         urlText = textField.getText();  
         //textArea.append(urlText);

         myModel.setURL(urlText);
         pageTitle = myModel.getTitle();
         myFrame.setTitle(pageTitle);
        pageBody = myModel.getBody();
        textArea.setText(pageBody); 
         System.out.println(pageBody); //This prints out exactly what Im wanting
                                       //  Its just a test             
         textArea.repaint();
    }
}
}

I'm guessing I maybe need to add something to my paintComponent since my TextArea is in a scrollPane that is attached to my Panel. I just really cant figure out what is wrong. If i put textArea.setText("blah"); it does what it should. The variable I am sending in is a very large string, its an entire webpage. Could that be the problem? With the code as is the textArea remains blank and what i'm wanting it to show prints correctly to the command line. HELP!

Edit here is the rest of my code

  import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;

public class BrowserFrame extends JFrame{

public BrowserFrame()
{
    BrowserPageReader myModel = new BrowserPageReader();
    setTitle("My Browser");
    Toolkit kit = Toolkit.getDefaultToolkit();
    Dimension screenSize =kit.getScreenSize();
    setSize(screenSize.width/2,screenSize.height-500);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = getContentPane();
    JTextField textField = new JTextField(20);
    BrowserPanel myPanel = new BrowserPanel(textField,myModel,this);
    contentPane.add(myPanel);
    contentPane.add(textField,BorderLayout.PAGE_START);
    setVisible(true);

}
}





 import javax.swing.*;
import java.io.*;
import java.net.*;

public class BrowserPageReader {

private URL myURL;
//private String webURL;
private String totalWebContent;
private String htmlString;
private String contentToPrint = " ";
private String urlPath;
private String urlHost;
private String pageTitle;
private String pageBody;
private String formattedBody;

public void setURL (String webURL)
{
   try{
        myURL = new URL(webURL);
        urlPath = myURL.getPath();
        urlHost = myURL.getHost();

    }
    catch(MalformedURLException e)
    {
        JOptionPane.showMessageDialog(null,"URL is incorrectly formatted");
    }
}

public void retrieveContent()
{
    try{
        Socket socket = new Socket(urlHost,80);
        PrintWriter out = new PrintWriter(socket.getOutputStream());
        BufferedReader in = new
                BufferedReader(new InputStreamReader(socket.getInputStream()));
        out.print("GET " + urlPath + " HTTP/1.1\n");
        out.print("Host: "+ urlHost + "\n");
        out.print("\n");
        out.flush();
        while((totalWebContent = in.readLine()) != null)
        {
            //System.out.println(totalWebContent);
            htmlString = htmlString + totalWebContent;
            //System.out.println(contentToPrint);
        }
        //System.out.println("htmlString\n" + htmlString);
    }
    catch(Exception e){
        e.printStackTrace();
    }
}

public String getTitle()
{
       retrieveContent();
      //System.out.println(htmlString);
      pageTitle = htmlString.substring(htmlString.indexOf("<title>")+ 7,
              htmlString.indexOf("</title>")); 
      return pageTitle;
}

public String getBody()
{
    String toDelete;
    String edited;
    retrieveContent();

    pageBody = htmlString.substring(htmlString.indexOf("<body")+5,
            htmlString.indexOf("</body>"));
    toDelete = pageBody.substring(0,pageBody.indexOf('<'));
    edited = pageBody.replace(toDelete,"");
    pageBody = edited
    formattedBody = pageBody.replaceAll("<[^>]*>", "");
    //System.out.println(formattedBody);
    return formattedBody;

}

Answer 1

Since your posted code is not an SSCCE, a small self-contained program that we can compile, run, and test, I don't think that we answer this without guessing. And so my guess: the JTextArea that you're adding text to is not the same one as is being displayed in a JFrame.

To be able to answer this with confidence though, we need that SSCCE, especially the code showing where you create the class above and where you add it to the JFrame that is displayed.

For instance, if I create a small SSCCE with mock BrowserFrame JFrame and BrowserPageReader model classes, everything seems to work fine:

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;

public class BrowserPanel extends JPanel {

   private JTextField textField;
   private String urlText;
   private JTextArea textArea;
   private BrowserPageReader myModel;
   private String pageContent;
   private BrowserFrame myFrame;
   private String pageTitle;
   private String pageBody;

   public BrowserPanel(JTextField myTextField, BrowserPageReader model,
         BrowserFrame frame) {
      myFrame = frame;
      myModel = model;
      textField = myTextField;
      textField.addActionListener(new InputHandler());

      /*
       * JScrollPane areaScrollPane = new JScrollPane(textArea);
       * areaScrollPane.setVerticalScrollBarPolicy(
       * JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
       * 
       * areaScrollPane.setPreferredSize(new Dimension(250,250));
       */
      textArea = new JTextArea(20, 40);
      textArea.setEditable(false);
      textArea.setWrapStyleWord(true);
      textArea.setLineWrap(true);
      JScrollPane scroll = new JScrollPane(textArea);

      add(scroll);
   }

   public void paintComponent(Graphics g) {
      super.paintComponent(g);

   }

   private class InputHandler implements ActionListener {
      public void actionPerformed(ActionEvent e) {
         urlText = textField.getText();
         // textArea.append(urlText);

         myModel.setURL(urlText);
         pageTitle = myModel.getTitle();
         myFrame.setTitle(pageTitle);
         pageBody = myModel.getBody();
         textArea.setText(pageBody);
         System.out.println(pageBody); // This prints out exactly what Im
                                       // wanting
                                       // Its just a test
         textArea.repaint();
      }
   }

   private static void createAndShowGui() {
      BrowserFrame frame = new BrowserFrame();
      JTextField textField = new JTextField(10);
      BrowserPageReader myModel = new BrowserPageReader();
      BrowserPanel mainPanel = new BrowserPanel(textField, myModel, frame);

      frame.add(textField, BorderLayout.NORTH);
      frame.add(mainPanel, BorderLayout.CENTER);

      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

class BrowserFrame extends JFrame {

}

class BrowserPageReader {

   public void setURL(String urlText) {
      // does nothing for now. for testing purposes.
   }

   public String getBody() {
      return "body"; // for testing purposes
   }

   public String getTitle() {
      return "title"; // for testing purposes
   }

}

Since my code "works" it proves that the error is not in the code you've posted above.

Your job is to post similar code that doesn't work fine, that instead demonstrates your problem. I'm guessing that if you put in the effort to create such a program, you'll isolate the error, you'll see where you've likely got two BrowserPanels, one displayed and one that is not displayed but is getting its text changed in the handler, and you'll be able to solve your error without our direct help.

---

Edit
SwingWorker e.g.

import javax.swing.*;
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.MalformedURLException;
import java.net.Socket;
import java.net.URL;

public class BrowserPanel extends JPanel {

   private JTextField textField;
   private String urlText;
   private JTextArea textArea;
   private BrowserPageReader myModel;
   private String pageContent;
   private BrowserFrame myFrame;
   private String pageTitle;
   private String pageBody;

   public BrowserPanel(JTextField myTextField, BrowserPageReader model,
         BrowserFrame frame) {
      myFrame = frame;
      myModel = model;
      textField = myTextField;
      textField.addActionListener(new InputHandler());

      /*
       * JScrollPane areaScrollPane = new JScrollPane(textArea);
       * areaScrollPane.setVerticalScrollBarPolicy(
       * JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
       * 
       * areaScrollPane.setPreferredSize(new Dimension(250,250));
       */
      textArea = new JTextArea(20, 40);
      textArea.setEditable(false);
      textArea.setWrapStyleWord(true);
      textArea.setLineWrap(true);
      JScrollPane scroll = new JScrollPane(textArea);

      add(scroll);
   }

   private class InputHandler implements ActionListener {
      public void actionPerformed(ActionEvent e) {
         urlText = textField.getText();
         // textArea.append(urlText);
         System.out.println(urlText);

         myModel.setURL(urlText);

         myModel.getContent(new PropertyChangeListener() {

            @Override
            public void propertyChange(PropertyChangeEvent evt) {
               if (SwingWorker.StateValue.DONE == evt.getNewValue()) {
                  pageTitle = myModel.getTitle();
                  myFrame.setTitle(pageTitle);
                  pageBody = myModel.getBody();
                  textArea.setText(pageBody);
                  System.out.println(pageBody);
               }
            }
         });
         // textArea.repaint();
      }
   }

   private static void createAndShowGui() {
      BrowserFrame frame = new BrowserFrame();
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

class BrowserFrame extends JFrame {

   public BrowserFrame() {
      BrowserPageReader myModel = new BrowserPageReader();
      setTitle("My Browser");
      Toolkit kit = Toolkit.getDefaultToolkit();
      Dimension screenSize = kit.getScreenSize();
      setSize(screenSize.width / 2, screenSize.height - 500);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      Container contentPane = getContentPane();
      JTextField textField = new JTextField(20);
      BrowserPanel myPanel = new BrowserPanel(textField, myModel, this);
      contentPane.add(myPanel);
      contentPane.add(textField, BorderLayout.PAGE_START);
      setVisible(true);

   }
}

class BrowserPageReader {

   private URL myURL;
   // private String webURL;
   private String totalWebContent;
   private String htmlString;
   private String contentToPrint = " ";
   private String urlPath;
   private String urlHost;
   private String pageTitle;
   private String pageBody;
   private String formattedBody;

   public void setURL(String webURL) {
      try {
         myURL = new URL(webURL);
         urlPath = myURL.getPath();
         urlHost = myURL.getHost();

      } catch (MalformedURLException e) {
         JOptionPane.showMessageDialog(null, "URL is incorrectly formatted");
      }
   }

   public void getContent(PropertyChangeListener listener) {
      RetrieveWorker worker = new RetrieveWorker();
      worker.addPropertyChangeListener(listener);
      worker.execute();
   }

   private void retrieveContent() {
      try {
         Socket socket = new Socket(urlHost, 80);
         PrintWriter out = new PrintWriter(socket.getOutputStream());
         BufferedReader in = new BufferedReader(new InputStreamReader(
               socket.getInputStream()));
         out.print("GET " + urlPath + " HTTP/1.1\n");
         out.print("Host: " + urlHost + "\n");
         out.print("\n");
         out.flush();
         while ((totalWebContent = in.readLine()) != null) {
            // System.out.println(totalWebContent);
            htmlString = htmlString + totalWebContent;
            // System.out.println(contentToPrint);
         }
         // System.out.println("htmlString\n" + htmlString);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }

   public String getTitle() {
      // !! retrieveContent();
      System.out.println(htmlString);
      pageTitle = htmlString.substring(htmlString.indexOf("<title>") + 7,
            htmlString.indexOf("</title>"));
      return pageTitle;
   }

   public String getBody() {
      String toDelete;
      String edited;
      // !! retrieveContent();

      pageBody = htmlString.substring(htmlString.indexOf("<body") + 5,
            htmlString.indexOf("</body>"));
      toDelete = pageBody.substring(0, pageBody.indexOf('<'));
      edited = pageBody.replace(toDelete, "");
      pageBody = edited;
      formattedBody = pageBody.replaceAll("<[^>]*>", "");
      // System.out.println(formattedBody);
      return formattedBody;

   }

   private class RetrieveWorker extends SwingWorker<Void, Void> {
      @Override
      protected Void doInBackground() throws Exception {
         retrieveContent();
         return null;
      }

   }
}

Answer 2

I bet your input handler is getting called multiple times. The text could be set to the body text, then print, then be set back to empty for some reason. Test this in your system.out.println statment by adding

System.out.println("outputStart: " + pagebody + " :END");

Then you'll be able to tell how many times your input handler ran.