Removing a highlight based on position in JTextComponent

Question

Hi smartypants' - In the contents of a JTextPane, I have highlighted individual lines of code (using DefaultHighlighter). Now when a user slaps their cursor down into a highlighted area of text, I want that to trigger the removal of a specific highlight. Don't know how to accomplish this though. The Highlighter interface offers a remove method if you happen to keep track of the tag Object returned by a prior call to addHighlight() but I would rather not correlate tags to cursor position (if such a thing can be done?)....
Thx,
Shawn

Answer 1

Position the caret on a highlight and click the 'Remove Highlight' button:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class TextPaneAttributes extends JFrame
     JTextPane textPane;
     public TextPaneAttributes()
          textPane = new JTextPane();
          StyledDocument doc = textPane.getStyledDocument();
          Highlighter.HighlightPainter painter =
               new DefaultHighlighter.DefaultHighlightPainter( Color.cyan );
          //  Set alignment to be centered for all paragraphs
          MutableAttributeSet standard = new SimpleAttributeSet();
          StyleConstants.setAlignment(standard, StyleConstants.ALIGN_CENTER);
          doc.setParagraphAttributes(0, 0, standard, true);
          //  Define a keyword attribute
          MutableAttributeSet keyWord = new SimpleAttributeSet();
          StyleConstants.setForeground(keyWord, Color.red);
          StyleConstants.setUnderline(keyWord, true);
          //  Add initial text
          textPane.setText( "one\ntwo\nthree \nfour\nfive\nsix\nseven\neight\n" );
          //  Change attributes on some keywords
          doc.setCharacterAttributes(0, 3, keyWord, false);
          doc.setCharacterAttributes(20, 4, keyWord, false);
          //  Highlight some text
          try
               textPane.getHighlighter().addHighlight( 4, 7, painter );
               textPane.getHighlighter().addHighlight( 25, 28, painter );
               textPane.getHighlighter().addHighlight( 35, 40, painter );
          catch(BadLocationException ble) {}
          //  Add some text
          try
               doc.insertString(0, "Start of text\n", null );
               doc.insertString(doc.getLength(), "End of text\n", keyWord );
          catch(Exception e) {}
          //  Add text pane to frame
          JScrollPane scrollPane = new JScrollPane( textPane );
          scrollPane.setPreferredSize( new Dimension( 200, 200 ) );
          getContentPane().add( scrollPane );
          //  Add a bold button
          JButton button = new JButton("Remove Highlight");
          getContentPane().add(button, BorderLayout.SOUTH);
          button.addActionListener( new ActionListener()
               public void actionPerformed(ActionEvent e)
//                    new StyledEditorKit.BoldAction().actionPerformed(null);
                    int offset = textPane.getSelectionStart();
                    System.out.println("\nCaret offset: " + offset);
                    Highlighter.Highlight[] highlights = textPane.getHighlighter().getHighlights();
                    for (int i = 0; i < highlights.length; i++)
                         Highlighter.Highlight h = highlights;
                         System.out.println( "Highlight offset: " + h.getStartOffset() );
                         if (offset >= h.getStartOffset()
                         && offset <= h.getEndOffset())
                              textPane.getHighlighter().removeHighlight(h);
     public static void main(String[] args)
          TextPaneAttributes frame = new TextPaneAttributes();
          frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
          frame.pack();
          frame.setVisible(true);