Swing/RollOverTree のバックアップ(No.12)

private final JTree tree = new JTree(makeModel()) {
  private final Color rolloverRowColor = new Color(220, 240, 255);
  private int rollOverRowIndex = -1;
  private transient MouseMotionListener listener;
  @Override public void updateUI() {
    removeMouseMotionListener(listener);
    super.updateUI();
    setCellRenderer(new DefaultTreeCellRenderer() {
      @Override public Component getTreeCellRendererComponent(
          JTree tree, Object value, boolean selected, boolean expanded,
          boolean leaf, int row, boolean hasFocus) {
        JComponent c = (JComponent) super.getTreeCellRendererComponent(
            tree, value, selected, expanded, leaf, row, hasFocus);
        if (row == rollOverRowIndex) {
          c.setOpaque(true);
          c.setBackground(rolloverRowColor);
          if (selected) {
            c.setForeground(getTextNonSelectionColor());
          }
        } else {
          c.setOpaque(false);
        }
        return c;
      }
    });
    listener = new MouseAdapter() {
      @Override public void mouseMoved(MouseEvent e) {
        int row = getRowForLocation(e.getX(), e.getY());
        if (row != rollOverRowIndex) {
          rollOverRowIndex = row;
          repaint();
        }
      }
    };
    addMouseMotionListener(listener);
  }
};