How to display bold text in only parts of JTextArea?

Can I alter the text of a JTextArea to bold (append text) and then back to normal and will it o开发者_运维百科nly display the bold text in bold and the rest as normal?

Also can the contents of JTextArea be saved as an RTF document?

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No. What you're looking for is JEditorPane

This supports HTML (3.2?) which will allow you to use <font> (and other older tags) to provide rich text.

JEditorPane textarea = new JEditorPane("text/html", "");
textarea.setText("Here is some <b>bold text</b>");

EDIT: According to the javadoc I referenced above, JEditorPane also supports limited RTF. Don't forget to change the MIME to text/rtf

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 textArea.setFont(textArea.getFont().deriveFont(Font.BOLD, textArea.getFont().getSize()));

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I believe you need a JTextPane or JEditorPane for that.