JTextArea.append

I have got some problem using the .append method of the JTextArea class. Below is my statement.
The declaration
private JTextArea ulist;
ulist = new JTextArea();
ulist.setFont(new Font("Tahoma", 0, 11));
ulist.setEnabled(false);
JScrollPane spulist = new JScrollPane(ulist);
spulist.setLocation(24, 285);
spulist.setSize(187, 150);
con.add(spulist);
spulist.append("Client" + clientno + "'s host name is" inetAddress.getHostName() "\n");
The error message i got was " cannot find symbol method in java.lang.string"
Can anyone help?

try ulist.append() rather than spulist.append. it
might workYes I rather think it will. I was hoping in reply 1 that the OP would spot the error of their ways with just a hint.

Similar Messages

JTextArea append problem

I have the following problem:
I am creating a JFrame with a JTextArea in it.
After all components are added to the JFrame
I call:
setLocation(100, 100);
pack();
setVisible(true);
Then a method is called that generates files and uses
jTextArea.append(".");
to add a "." to the JTextArea for each created file
to show the progress.
Now the problem is that the dots are not shown one after the other.
The window pops up AFTER all the dots are written and not when
setVisible(true);
is called.
What do I have to do that every single dot is shown in the
JTextArea right after it is appended ?

Move your actual file generating process to a different thread. The best way to do it is using SwingWorker. There is a tutorial on the Sun's web site at http://java.sun.com/docs/books/tutorial/uiswing/misc/threads.html that demonstrates how to use SwingWorker.
Hope this helps
Sai Pullabhotla

Question on JTextArea.append(String str)

Hi All,
When i provide JTextArea.append("FMTL") it is showing me on the JTextArea but when i give it as
String item="Viswanadh";
JTextArea.append(item).this particular statement is remaming blank on the TextArea.
Any idea why this is happening and is there any other method to be used instead of append.???
Thanks in advance..
regards,
Viswanadh

class OnApplyFormat implements ActionListener{
     public void actionPerformed(ActionEvent formatevent){
          JComboBox source = (JComboBox) formatevent.getSource();
               String item = source.getSelectedItem().toString();
                 System.out.println("Selected Format is:"+item);
                 try
                   if ( item!=null )
                          System.out.println("Format is:"+item);
                 infoarea.append("FMTL");
               infoarea.append(item);
                 infoarea.append("\r\n");
               infoarea.append("FMTU");
               infoarea.append("\r\n");
               infoarea.append("wait 5");
               infoarea.append("\r\n");
          else
               throw new Exception("FormatNotFoundException");
                      }catch(Exception e){
                      e.printStackTrace();
}That is my code and still i am facing the same FMTL is not getting appended with the item variable.
Help me in solving this issue.
Thanks in advance.
regards,
Viswanadh

Doubt to be Clarified on JTextArea appending a string

Hi All,
Here is the actual code.
String msg="Settings Details Will be Produced after the Connection is Successful";
                    String msg1=      "-------------------------------------------------------------------------";
                    String comdetails="1)Comport Enabled is:";
                    String baudratedetails="2)BaudRate Selected is:";
                    String databitdetails="3)DataBit is:";
                    String paritybitdetails="4)ParityBit is:";
                    String stopbitdetails="5)Stopbit is:";
contentarea.setText("");
                       contentarea.append(msg);
                    contentarea.append("\r\n");
                    contentarea.append(msg1);
                    contentarea.append("\r\n");
                    contentarea.append(msg1);
                    contentarea.append("\r\n");
                    contentarea.append(comdetails);contentarea.append(cv);
                    contentarea.append("\r\n");
                    contentarea.append(baudratedetails);contentarea.append(bv);
                    contentarea.append("\r\n");
                    contentarea.append(databitdetails);contentarea.append(dv);
                    contentarea.append("\r\n");
                    contentarea.append(paritybitdetails);contentarea.append(pv);
                    contentarea.append("\r\n");
                    contentarea.append(stopbitdetails);contentarea.append(sv);
                    contentarea.append("\r\n");
                    contentarea.append(msg1);
                    contentarea.append("\r\n");
                    contentarea.append(msg1);I have a JTextArea which is basically linked up with a JBUtton.So when i click on JButton in the JTextArea thte following will be displayed.
"Settings Details Will be Produced after the Connection is Successful"
1)Comport Enabled is:COM3
2)BaudRate Selected is:38400
3)DataBit is:8bit
4)ParityBit is:NONE
5)Stopbit is:1bitSo my question when i again click on the same JButton the same data which is highlighted in the code tags need to be displayed again from the next end line of the previous data instead of overriding operation.Can any one help me out in doing this???
Thanks in advance.
regards,
Viswanadh

Hi toodburch,
Thanks for the reply.My requirement is for every click on the JButton it should be in the following way.Assume i have pressed 3 times.then it should be displayed as shown.
"Settings Details Will be Produced after the Connection is Successful"
1)Comport Enabled is:COM3
2)BaudRate Selected is:38400
3)DataBit is:8bit
4)ParityBit is:NONE
5)Stopbit is:1bit
"Settings Details Will be Produced after the Connection is Successful"
1)Comport Enabled is:COM3
2)BaudRate Selected is:38400
3)DataBit is:8bit
4)ParityBit is:NONE
5)Stopbit is:1bit
"Settings Details Will be Produced after the Connection is Successful"
1)Comport Enabled is:COM3
2)BaudRate Selected is:38400
3)DataBit is:8bit
4)ParityBit is:NONE
5)Stopbit is:1bitThanks
regards,
Viswanadh

JTextArea can't append

I need to append text to a JTextArea from a different class than the JTextArea is in. For example, my code is as follows:
public JTextArea getJTextArea() {
if (jTextArea == null) {
jTextArea = new JTextArea();
jTextArea.setBounds(new java.awt.Rectangle(115,8,274,181));
jTextArea.setBorder(javax.swing.BorderFactory.createLineBorder(java.awt.Color.gray,1));
jTextArea.setText("Chat initiated...");
jTextArea.append("append");
          return jTextArea;
Appending the text works in the above code, but if I try to append text using this code:
jTextArea.append("appended text");
anywhere else in the code it will not work. Why is this and how do I append text to the jTextArea?

You can't expect one class to recognize a variable declared elsewhere, right?
class Freader {
    public static void main(String args[]){
        jTextArea.append("new text"); //out of nowhere!
}This really isn't a Swing question, it's a "how can I write code" question.
To send message append (for example) to object jTextArea
and do this from within method m of class C, then either:
1. Create the object referred to by jTextArea in method m.
2. Have jTextArea passed into method m
3. Have jTextArea be a field of class C
4. Invoke some other method that returns the reference to jTextArea.
5. Don't do this directly in m: invoke another method that does
it directly or indirectly.
Do you get the idea?
For example, Below I define Main, which will invoke append, and Display,
which has the append method.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Main {
    public static void main(String[] args) {
        final JFrame f = new JFrame("Main");
        JButton btn = new JButton("append");
        btn.addActionListener(new ActionListener(){
            Display display = new Display(f);
            public void actionPerformed(ActionEvent evt) {
                display.append("some more text\n");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.getContentPane().add(btn);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
class Display {
    public Display(JFrame owner) {
        JDialog dialog = new JDialog(owner, "Display");
        textComponent = new JTextArea(20, 50);
        dialog.getContentPane().add(new JScrollPane(textComponent));
        dialog.pack();
        dialog.setVisible(true);
    public void append(String text) {
        textComponent.append(text);
    private JTextArea textComponent;
}

Bit of a pickle (to use JTextArea or JTextPane)

Basically what i'm trying to do is print out array of numbers into a JTextArea or JTexPane. Initially i started printing into a JTextArea. This work fine, it printed without problems. However, i needed to center this prints and i couldn't do that in an JTextArea. So i started to use JTextPane, the center worked, but i could only print one number, it kept overriding the previous one. How would i print into a JTextPane?
Any help is appreciated :)
JTextPane text = new JTextPane();
SimpleAttributeSet set = new SimpleAttributeSet();
StyledDocument doc = text.getStyledDocument();
StyleConstants.setAlignment(set,StyleConstants.ALIGN_CENTER);
text.setParagraphAttributes(set,true);
JTextArea printArea = new JTextArea(10, 10);
for (int i = 0; i < arr.length; i++) {
      printArea.append(arr[i] + ", "); //Works fine, but no center
      text.setText(arr[i] + " "); //Doesn't print properly...
printArea.append("\n");
text.setText("\n");

For the JTextPane, you were calling setText(), which overrides the current text and replaces it entirely with new text. You should instead append directly to the end of its document (Check the source for JTextArea#append(); that's what it's doing as well). You also need to be adding a newline character between printed numbers:
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
public class JTextPaneCentering extends JFrame {
     private static final int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
     public JTextPaneCentering() {
          JPanel cp = new JPanel(new BorderLayout());
          cp.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
          JTextPane text = new JTextPane();
          SimpleAttributeSet set = new SimpleAttributeSet();
          StyleConstants.setAlignment(set, StyleConstants.ALIGN_CENTER);
          text.setParagraphAttributes(set,true);
          for (int i = 0; i < arr.length; i++) {
               append(text, arr[i] + "\n");
          cp.add(new JScrollPane(text));
          setContentPane(cp);
          setDefaultCloseOperation(EXIT_ON_CLOSE);
          setTitle("JTextPane Text Centering");
          pack();
    public void append(JTextPane textPane, String str) {
          Document doc = textPane.getDocument();
          if (doc != null) {
               try {
                    doc.insertString(doc.getLength(), str, null);
               } catch (BadLocationException e) {
                    // Never happens.
     public static void main(String[] args) {
          SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                    new JTextPaneCentering().setVisible(true);
}

JTextField and append

hi,
i've got a question: I'm looking a method in JTextField class similar to the append() in JTextArea.
I need to add a new chars to the end of my text in TextField. The method setText() doesn't work - it always clear the field and set the text at the beginning of my TextField
thanks a lot in advance
thud
Message was edited by:
thud_Mike

In the future, you can always look at the source code to see what the JTextArea append() method does and then use the same concept on JTextField.
Document doc = textComponent.getDocument();
doc.insertString( doc.getLength(), "whatever", null );

JTextArea update VERY slow

I have a dialog that a JTabbedPane with several tabs on it. One of the tabs contains a JTextArea that I have redirected System.out to. The JTextArea is attached to a JScrollPane and then to the JTabbedPane. The class I created to send System.out to the JTextArea does a JTextArea.append() to display the information in the JTextArea. I am NOT trying to scroll the JScrollPane to keep the last message displayed or anything like that.
The problem is, when I write a large amount of data (30-50 lines, each line <60 characters) to the JTextArea (with System.out.println()) my application becomes unresponsive and it takes a very long time to display. This is only an issue when I have selected the tab in the JTabbedPane that contains my JTextArea. If I select another tab, writing a large amount of data to System.out has no noticeable affect on my application and it displays very quickly.
Is there a better way to update the JTextArea than to use JTextArea.append()? The append() method seems to invalidate the entire JTextArea for each line or character that is displayed (even when the text is not actually displayed on the screen) and slows things down a lot.

I can't really say that it is that exciting but, here it is
import java.awt.*;
import java.io.*;
import javax.swing.*;
import javax.swing.text.*;
public class GUIStream extends OutputStream {
     private JTextArea               _area     = new JTextArea();
     private JScrollPane               _pane     = new JScrollPane( _area );
     public GUIStream() {
          _pane.setPreferredSize( new Dimension( 450, 125 ) );
          _area.setEditable( false );
     public JComponent getOutput() {
          return _pane;
     public void write( int b ) {
          String out;
          try {
               out = Integer.toString( b );
          catch( Exception e ) {
               return;
          _area.append( out );
          _area.invalidate();
     public void write( byte[] buf ) throws IOException {
          write( buf, 0, buf.length );
     public void write( byte[] buf, int off, int len ) {
          _area.append( new String( buf, off, len ) );
          _area.invalidate();
     public void clear() {
          _area.setText( "" );
}To redirect System.out, i simply did this:
System.setOut( new PrintStream( new BufferedOutputStream( new GUIStream() ), false );To add the Component to a dialog, or whatever, use GUIStream.getOutput().

JTextArea within a JScrollPane

Hi!
I've searched through the Project Swing archive and found lots of questions regarding how you ensure that when text is entered into a JTextArea control (via the append() method) the JScrollPane automatically scrolls to the position where the text was appended.
Unfortunately I haven't yet found a satisfactory solution to this issue.
I have a JTextArea control within a JScrollPane control. I start a seperate thread in order to perform some processing. This operation being run within this thread needs to provide progress information to the user and I present this progress information via the JTextArera control. Although the information is displayed within the JTextArea the JScrollPane unfortunately doesn't scroll down so that the last message entered into the JTextArea is visible. The user needs to scroll down manually in order to see the messages.
I have read that if you invoke JTextArea.setText() or JTextArea.append() from within a thread otherthan the event dispatching thread then the JScrollPane will have no knowledge that text as been added. The article suggested using SwingUtilities.invokeLater(Runnable run) to ensure that the call to JTextArea.setText() or JTextArea.append() is performed within the event dispatching thread. I did create a Runnable class whose sole purpose was to call JTextArea.append() with message information but still the JScrollPane fails to automatically scroll as successive lines of text are being added to the JTextArea control.
Can somebody please shed some light on my problem?

Here's a simple program that works for me. Note, if you comment out the setCaretPosition() method it stops working.
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
public class TestTextArea extends JFrame
     JTextArea textArea;
public TestTextArea()
     JPanel panel = new JPanel();
     setContentPane( panel );
     panel.setPreferredSize( new Dimension( 200, 200 ) );
          textArea = new JTextArea( "one two", 3, 15 );
          JScrollPane scrollPane = new JScrollPane( textArea );
          panel.add( scrollPane );
          JTextArea textArea2= new JTextArea( "abcd", 3, 15 );
          textArea2.setPreferredSize( new Dimension( 50, 10 ) );
          panel.add( textArea2 );
     public void updateTextArea2()
          int line = 0;
          while ( true )
               textArea.append( "\nline: " + ++line );
               textArea.setCaretPosition( textArea.getText().length() );
               try
                    Thread.sleep(1000);
               catch (Exception e) {}
public static void main(String[] args)
TestTextArea frame = new TestTextArea();
frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
frame.pack();
frame.setVisible(true);
          frame.updateTextArea2();

Java.lang.Error in JTextArea

I get a strange error while using JTextArea.append(String), more specifically, an error while trying to aquire writing lock. The error never show up at a precise time and sometimes just never show so I guess this is a multithread issue. However I already tried to synchronize on the text area, enqueue messages to print in a slave thread so that only one thread ever do the append, but nothing fix it.
Does any of you already had this error or have any insight on a possible way to fix it?
Regards

No only one... puzzling, here is the code:
import java.awt.Color;
import java.awt.event.FocusListener;
import java.awt.event.MouseWheelListener;
import java.util.LinkedList;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class ConsolePane extends JScrollPane
     private static final int MAX_LINE = 120;
     private int max;
     private boolean follow;
     private JTextArea area;
     private ConsoleWriter writer;
     public ConsolePane()
          this(MAX_LINE);
     public ConsolePane(int max)
          if( max <= 0 )
               throw new IllegalArgumentException("Null or negative max amount");
          this.max = max;
          area   = new JTextArea();
          writer = new ConsoleWriter();
          follow = false;
          area.setEditable(false);
          setViewportView(area);
          writer.start();
     public void addKeyListener(java.awt.event.KeyListener l)
          area.addKeyListener(l);
     public void addFocusListener(FocusListener l)
          super.addFocusListener(l);
          if( area != null )
               area.addFocusListener(l);
     public void addMouseWheelListener(MouseWheelListener l)
          super.addMouseWheelListener(l);
          if( area != null )
               area.addMouseWheelListener(l);
     protected void finalize()
          if( writer != null )
               writer.kill();
     public boolean followLastLine()
          return follow;
     public int getMaxShownLines()
          return max;
     public String getSelectedText()
          return area.getSelectedText();
     public boolean isFocusOwner()
          return super.isFocusOwner() || area.isFocusOwner();
     public void print(String s)
          if( s == null )
               s = "null";
          writer.enqueue(s);
     public void setBackground(Color bg)
          super.setBackground(bg);
          if( area != null )
               area.setBackground(bg);
     public void setFollowLastLine(boolean f)
          follow = f;
          if( follow )
               showLastLine();
               repaint();
     public void setForeground(Color fg)
          super.setForeground(fg);
          if( area != null )
               area.setForeground(fg);
     public void showLastLine()
          try{area.setCaretPosition(area.getLineStartOffset(area.getLineCount() - 1));
          }catch(Exception e){}
     public void setMaxShownLines(int max)
          if( max <= 0 )
               throw new IllegalArgumentException("Null or negative max amount");
          else
               this.max = max;
     private class ConsoleWriter extends Thread
          private boolean stop;
          private LinkedList pending;
           * Constructor for Writer.
          ConsoleWriter()
               super("Console writer");
               stop = false;
               pending = new LinkedList();
          void enqueue(String s)
               if( s == null )
                    throw new IllegalArgumentException("Null string");
               if( s.length() > 0 )
                    pending.addLast(s);
                    if( !isInterrupted() )
                         interrupt();
          void kill()
               if( !stop )
                    stop = true;
                    if( !isInterrupted() )
                         interrupt();
          public void run()
               while(!stop)
                    try{sleep(3600000);}catch(Exception e){}
                    while(pending.size() > 0)
                         write((String)pending.removeFirst());
                         yield();
          private void write(String s)
               if( area.getText().length() == 0 && s.charAt(0) == '\n' )
                    area.append(s.substring(1));
               else
                    area.append(s);
               int excedent = area.getLineCount() - ConsolePane.this.max;
               if( excedent > 0 )
                    try{JonsolePane.this.area.getDocument().remove(0, ConsolePane.this.area.getLineStartOffset(excedent));}catch(Throwable t){}
               if( ConsolePane.this.followLastLine() )
                    ConsolePane.this.showLastLine();
               interrupted();
}

Re: HELP How to Display on JTextArea

Don't forget to use the Code Formatting Tags so the posted code retains its original formatting. That is done by selecting the code and then clicking on the "Code" button above the question input area.
Use the JTextArea.append(...) method to append text the text area in tha ActionListener.

the new version is rumored to give the developers a little more access to displays, but it is still on an app by app basis. You would need to contact the developer of the app your interested in to see if they are going to implement it. (yes this includes apple, but they are most likely not going to give full access to display yet)
Jason

How to add a line using JTextArea?

I want to add the message to a component from row start. which method can I use to add as line?
sirius

Thank you very much. Just now I try to append the control char in the end of str. It is successful. see the follow:
String CRLF = System.getProperty("line.separator")
//here the CRLF is control char.
while (true) {
JTextArea.append(Str + CRLF);
//next time the string can be appended from a new line. :)
//bow

Overriding JTextArea default behavior..

Greetings and Salivations..
I'm having a bit of trouble trying to figure out how to override a JTextArea's behavior...specifically, when you hit enter while focused on the object.
JTextArea appends a new line (of course) in the text area when you hit enter - I need to override this somehow and make it not happen...like have it return false or something magical like that.
spankshoesberrycrunch

http://java.sun.com/docs/books/tutorial/uiswing/events/documentlistener.html

Java Front End, PHP Back End

Hi all, I am trying to create a java front end with a php back end. Using a tip from Core Java Technologies Tech Tips (http://java.sun.com/developer/JDCTechTips/2004/tt0210.html#2). I tried to convert their code from a command line to a GUI and have gotten preaty far but it is only allowing me to get one row of data from the php file. Here is my code so far:
package test;
import java.net.URL;
import java.net.MalformedURLException;
import java.net.URLConnection;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
* @author bdeonline
public class test extends javax.swing.JFrame {
private static URLConnection connection;
private String inputLine;
private static void connect( String urlString ) {
try {
URL url = new URL(urlString);
connection = url.openConnection();
} catch (MalformedURLException e){
} catch (IOException e) {
private String readContents() {
BufferedReader in = null;
try {
in = new BufferedReader(
new InputStreamReader(
connection.getInputStream()));
String inputLine;
while (
(inputLine = in.readLine()) != null) {
return(inputLine);
} catch (IOException e) {
return inputLine;
/** Creates new form test */
public test() {
initComponents();
/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
private void initComponents() {
jButton1 = new javax.swing.JButton();
jScrollPane1 = new javax.swing.JScrollPane();
jTextArea1 = new javax.swing.JTextArea();
addWindowListener(new java.awt.event.WindowAdapter() {
public void windowClosing(java.awt.event.WindowEvent evt) {
exitForm(evt);
jButton1.setText("jButton1");
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
getContentPane().add(jButton1, java.awt.BorderLayout.SOUTH);
jScrollPane1.setViewportView(jTextArea1);
getContentPane().add(jScrollPane1, java.awt.BorderLayout.CENTER);
pack();
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
connect("http://localhost/test.php");
jTextArea1.setText(readContents());
/** Exit the Application */
private void exitForm(java.awt.event.WindowEvent evt) {
System.exit(0);
* @param args the command line arguments
public static void main(String args[]) {
new test().show();
// Variables declaration - do not modify
private javax.swing.JButton jButton1;
private javax.swing.JScrollPane jScrollPane1;
private javax.swing.JTextArea jTextArea1;
// End of variables declaration
I am preaty new at java, I know PHP preaty well though so something like this could help me out alot. Most of this code was generated with the help of Netbeans.

I dont see why it would unles it has something to do with your URLConnection being static. setText() is only going to give you one line as well. try
jTextArea.append(inputLine);
and make only one declairation of inputLine.
The only thing that should be static in your code is the main method.

[APPLET][Heritage] Problem with classes

Hi, I'm developping a simple JAVA Applet and I have a problem
I have a class called LUIweb which is the main class. Here is a part of it.
public class LUIweb extends JApplet implements Runnable {
public void run() {
DisplayMessage("JAVA rocks");
public void DisplayMessage(String message){
jtextArea.append(message);
middlePanel.removeAll();
middlePanel.add(textScrollPane, BorderLayout.CENTER);
middlePanel.validate();
middlePanel.repaint();
It displays the message "JAVA rocks" in my JTextArea. But when another class from the same package calls DisplayMessage, nothing is displayed in my JTextArea
public class Data_net extends LUIweb{
public void Test(){
DisplayMessage("NON");
Have you got any idea to fix that?
Thank you for you help

OK,
You are using a separate thread to update the gui. As swing is not multithread safe, this is not good. Anytime you want to change the gui, you must do it on the gui thread. This means without extra help, you should only change the gui from within a Listener, such as a MouseListener, KeyListener, etc, etc.
In your case, you are updating the not from the gui thread (not from a Listener), and so you must ask the gui thread to do the work for you when it has time.
This means you need to use SwingUtilities.invokeLater or SwingUtilities.invokeAndWait.
Since the sequencing is important to you in your code, you should probably use invokeAndWait, such as
public void run()
          SwingUtilities.invokeAndWait( new Runnable()
                 public void run() { DisplayMessage(Language.CONNECT_DB); }
          Data_net Donnee_net=new Data_net();
          SwingUtilities.invokeAndWait( new Runnable()
                 public void run() { DisplayMessage("Connecting to "+Donnee_net.GetHost()+
                                                   " with user "+Donnee_net.GetUser()+"...\n");
          Donnee_net.Test();

JTextArea.append

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