JOptionPaneに配置するJTextAreaの最大幅を指定してサイズ調整を行う

private final JTextArea textArea = new JTextArea(1, 1) {
  @Override public void updateUI() {
    super.updateUI();
    setLineWrap(true);
    setWrapStyleWord(true);
    setEditable(false);
    setOpaque(false);
    // setBorder(BorderFactory.createLineBorder(Color.RED));
    setFont(new Font(Font.MONOSPACED, Font.PLAIN, 12));
  }

  @Override public void setText(String t) {
    super.setText(t);
    try {
      setColumns(50);
      // javax/swing/text/JTextComponent.html#modelToView-int-
      // i.e. layout cannot be computed until the component has been sized.
      // The component does not have to be visible or painted.
      setSize(super.getPreferredSize()); // setSize: looks like ugly hack...
      System.out.println(super.getPreferredSize());

      Rectangle r = modelToView(t.length());
      int rc = (int)(.5 + (r.y + r.height) / (float) getRowHeight());
      setRows(rc);
      System.out.format("Rows: %d%n", rc);
      System.out.println(super.getPreferredSize());
      if (rc == 1) {
        setSize(getPreferredSize());
        setColumns(1);
      }
    } catch (BadLocationException ex) {
      ex.printStackTrace();
    }
  }
};