// -*- mode:java; encoding:utf-8 -*-
// vim:set fileencoding=utf-8:
// @homepage@

package example;

import java.awt.*;
import java.util.stream.Stream;
import javax.swing.*;

public final class MainPanel extends JPanel {
  private MainPanel() {
    super(new BorderLayout());

    JComboBox<String> combo = new JComboBox<>(new String[] {"AAAAA", "BBBB", "CCC", "DD", "E"});
    combo.setSelectedIndex(-1);

    JButton b1 = new JButton("setSelectedIndex(0)");
    JButton b2 = new JButton("setSelectedIndex(-1)");
    JButton b3 = new JButton("setSelectedItem(null)");

    b1.addActionListener(e -> combo.setSelectedIndex(0));
    b2.addActionListener(e -> combo.setSelectedIndex(-1));
    b3.addActionListener(e -> combo.setSelectedItem(null));

    JPanel box = new JPanel(new GridLayout(0, 1, 10, 10));
    Stream.of(b1, b2, b3, combo).forEach(box::add);

    add(box, BorderLayout.NORTH);
    setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
    setPreferredSize(new Dimension(320, 240));
  }

  public static void main(String[] args) {
    EventQueue.invokeLater(MainPanel::createAndShowGui);
  }

  private static void createAndShowGui() {
    try {
      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    } catch (UnsupportedLookAndFeelException ignored) {
      Toolkit.getDefaultToolkit().beep();
    } catch (ClassNotFoundException | InstantiationException | IllegalAccessException ex) {
      ex.printStackTrace();
      return;
    }
    JFrame frame = new JFrame("@title@");
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    frame.getContentPane().add(new MainPanel());
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
  }
}
