How to force a scrollbar to scroll down by itself

[Jimguld]

Hi , I have a JTextarea that I add text to every time I press a button. But I can't seem to get the textarea to scroll down by itself so I can see the last added line.

I have tried going about the viewport, but it sucks a bit.
Any suggestions

Tried this..but not really good

JViewport port = (JViewport)scrollreply.getViewport();
port.scrollRectToVisible(port.getViewRect());

 

[titanandrews]

Try setCaretPosition() from the JTextArea. Hope it helps!



Barry

 

[Jimguld]

Okay fine, but how do I use it...which position do I provide

 

[titanandrews]

Using the crude code below the automatic scrolling works for me, even without calling setCaretPosition(). Is this what you need?


regards,

Barry

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

public class AutoScroll
{
    private static JTextArea textArea;

    public static void main(String [] args)
    {
        JButton addButton = new JButton("Add");        

        textArea = new JTextArea();
        JScrollPane pane = new JScrollPane(textArea,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);        

        JFrame frame = new JFrame();
        frame.setSize(300,300);
        frame.setLocation(200,200);

        JPanel north = new JPanel();
        north.setLayout(new GridLayout());
        north.setPreferredSize(new Dimension(280,200));
        north.add(pane);

        JPanel south = new JPanel();
        south.setLayout(new GridLayout());
        south.add(addButton);

        Container c = frame.getContentPane();
        c.add(north,"North");
        c.add(south,"South");

        addButton.addActionListener(new ActionListener()
            {                
                public void actionPerformed(ActionEvent e)
                {
                    //Add some text
                    textArea.setText(textArea.getText() + "Adding some text \n");
                    //textArea.setCaretPosition(textArea.getText().length());
                }
            });

        frame.show();
    }
}

 

[Jimguld]

Thanks, using

textArea.setCaretPosition(textArea.getText().length());


this works works. It does not work without, strange I think....

Cheers
Jim

 

[titanandrews]

Hmmmmmmmm... Which SDK are you using? I have 1.3.1.08 and 1.4.0. It works fine for me on both versions without the setCaretPosition(). Also which OS? I am using Windows 2000.



Barry

 

[Jimguld]

I may be a bit out of time...I am using C:\jdk1.3.0_01

maybee this could be the problem.

 

[titanandrews]

I would say that is the problem. If you are forced to use that version, then you can just use the setCaretPosition()


Barry