Java Swing How to - Set different colors for text and underline in JTextPane

Question

We would like to know how to set different colors for text and underline in JTextPane.
Answer

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Shape;
//  w  ww.j a  v a2s  .  c o m
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.plaf.basic.BasicTextPaneUI;
import javax.swing.text.AbstractDocument;
import javax.swing.text.BoxView;
import javax.swing.text.ComponentView;
import javax.swing.text.Element;
import javax.swing.text.IconView;
import javax.swing.text.LabelView;
import javax.swing.text.MutableAttributeSet;
import javax.swing.text.ParagraphView;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyledDocument;
import javax.swing.text.StyledEditorKit;
import javax.swing.text.View;
import javax.swing.text.ViewFactory;

public class Main {
  public static void main(String args[]) {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JTextPane pane = new JTextPane();
    pane.setEditorKit(new CustomEditorKit());
    pane.setText("Underline With Different Color");

    StyledDocument doc = (StyledDocument) pane.getDocument();
    MutableAttributeSet attrs = new SimpleAttributeSet();
    attrs.addAttribute("Underline-Color", Color.red);
    doc.setCharacterAttributes(0, doc.getLength() - 1, attrs, true);

    JScrollPane sp = new JScrollPane(pane);
    frame.setContentPane(sp);
    frame.setPreferredSize(new Dimension(400, 300));
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }

}

class CustomEditorKit extends StyledEditorKit {

  public ViewFactory getViewFactory() {
    return new CustomUI();
  }
}

class CustomUI extends BasicTextPaneUI {
  @Override
  public View create(Element elem) {
    View result = null;
    String kind = elem.getName();
    if (kind != null) {
      if (kind.equals(AbstractDocument.ContentElementName)) {
        result = new MyLabelView(elem);
      } else if (kind.equals(AbstractDocument.ParagraphElementName)) {
        result = new ParagraphView(elem);
      } else if (kind.equals(AbstractDocument.SectionElementName)) {
        result = new BoxView(elem, View.Y_AXIS);
      } else if (kind.equals(StyleConstants.ComponentElementName)) {
        result = new ComponentView(elem);
      } else if (kind.equals(StyleConstants.IconElementName)) {
        result = new IconView(elem);
      } else {
        result = new LabelView(elem);
      }
    } else {
      result = super.create(elem);
    }
    return result;
  }
}

class MyLabelView extends LabelView {

  public MyLabelView(Element arg0) {
    super(arg0);
  }

  public void paint(Graphics g, Shape a) {
    super.paint(g, a);
    Color c = (Color) getElement().getAttributes().getAttribute(
        "Underline-Color");
    if (c != null) {
      int y = a.getBounds().y + (int) getGlyphPainter().getAscent(this);
      int x1 = a.getBounds().x;
      int x2 = a.getBounds().width + x1;

      g.setColor(c);
      g.drawLine(x1, y, x2, y);
    }
  }
}