Question

I am trying to build a chat client that uses JTextPane to display the conversations. I am having problems with highlighting the past sentences of a chat-participant chosen by the user. When implementing this I need to stick to using HTMLDocument as some of the content has to be HTML.

The best idea seemed to be using a different named styles for each user participating in the conversation. The idea is that when the text of a particular person needs to be highlighted, I just update his personal style and everything he has said should get highlighted as by magic. Unfortunately this does not work.

So to add text I use:

public void addMessage(String from, String message){
    HTMLDocument doc = (HTMLDocument) textPane.getStyledDocument();
    if(doc != null){
        try {
            String stylename = "from_" + from;
            if(textPane.getStyle(stylename) == null){
                LOG.debug("Did not find style. Adding new: " + stylename);
                Style nameStyle = textPane.addStyle(stylename, null);
                StyleConstants.setForeground(nameStyle, Color.black);
                StyleConstants.setBold(nameStyle, true);
            }else{
                LOG.debug("Found existing style: " + textPane.getStyle(stylename));
            }
            doc.insertString(doc.getLength(), from + ": ", textPane.getStyle(stylename));
            doc.insertString(doc.getLength(), message + "\n", null);
        } catch (BadLocationException ble) {
            LOG.error("Could not insert text to tab");
        }
    }
}

So far so good… The text gets displayed in the textPane as I wished. However when I try to update the stylesheet at some future point and call:

public void highlight(String name, boolean highlight){
    Style fromStyle = textPane.getStyle("from_" + name);
    if(fromStyle != null){
        LOG.debug("found style, changing color");
        StyleConstants.setForeground(fromStyle, Color.red);
    }else{
        LOG.debug("fromStyle was NULL");
    }
}

..I can see that the style is found and my code gets executed – yet nothing changes on the screen.

I would like to ask if you have any suggestions on how I might try to resolve this issue. Is there a way to make this work with named styles or should I take some completely different approach?

Thank you

Answer 1

You just modified the Style object, you still have to apply the modified Style using setCharacterAttributes.