How to set AUTO-SCROLLING of JTEXTAREA in Java GUI?

Question

I have embedded a JTextArea on a JScrollPane and am using that JTextArea for output.

I want that whenever the ouput goes beyond the size of the JTextArea, the JTextArea scrolls automatically so that user don't have to do manual scroll down to see the recent output.

How can I do that?

I have already set the autoscroll property of both JTextArea and JScrollPane to true.

Answer 1

Text Area Scrolling

In response to the comment, the basics of the link are:

When using JDK1.4.2 (or earlier) the most common suggestion you will find in the forums is to use code like the following:

textArea.append(...);
textArea.setCaretPosition(textArea.getDocument().getLength());

However, I have just noticed that in JDK5 this issue has actually been resolved by an API change. You can now control this behaviour by setting a property on the DefaultCaret of the text area. Using this approach the code would be:

JTextArea textArea = new JTextArea();
DefaultCaret caret = (DefaultCaret)textArea.getCaret();
caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);

As a side note can anybody tell me why I am not receiving email notifications when comments are added to my replies. I've checked the "I'd like email notifications of activity on my questions and answers" checkbox on my preferences page. And I've double checked my email address. Is there anything else I need to do?

Answer 2

    JScrollBar vbar = scrollPane.getVerticalScrollBar();

    for (int i = 0; i < 20; i++) {

        myJTxt.append("This is text " + i + "\n");
        vbar.setValue(vbar.getMaximum());
        vbar.paint(vbar.getGraphics());
        myJTxt.scrollRectToVisible(myJTxt.getVisibleRect());
        myJTxt.paint(myJTxt.getGraphics());
        try {
            Thread.sleep(250);
        } catch (InterruptedException ex) {
            Logger.getLogger(ScrollTextView.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

Answer 3

Thank you very much "DefaultCaret" really working :) ans hass solved my problem which was hunting me for some years.