package ch02.section06;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class ListTest
    extends JPanel
    implements ListSelectionListener {
  private JList list;
  private DefaultListModel listModel;

  private static final String addString = "增 加";
  private static final String delString = "刪 除";
  private JButton fireButton;
  private JTextField employeeName;

  public ListTest() {
    super(new BorderLayout());

    listModel = new DefaultListModel();
    listModel.addElement("北京市");
    listModel.addElement("天津市");
    listModel.addElement("重慶市");
    listModel.addElement("深圳市");
    listModel.addElement("廣州市");
    listModel.addElement("上海市");

    //創(chuàng)建一個(gè)列表并將它放在一個(gè)滾動(dòng)面板中
    list = new JList(listModel);
    list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    list.setSelectedIndex(0);
    list.addListSelectionListener(this);
    list.setVisibleRowCount(5);
    JScrollPane listScrollPane = new JScrollPane(list);

    JButton hireButton = new JButton(addString);
    HireListener hireListener = new HireListener(hireButton);
    hireButton.setActionCommand(addString);
    hireButton.addActionListener(hireListener);
    hireButton.setEnabled(false);

    fireButton = new JButton(delString);
    fireButton.setActionCommand(delString);
    fireButton.addActionListener(new FireListener());

    employeeName = new JTextField(10);
    employeeName.addActionListener(hireListener);
    employeeName.getDocument().addDocumentListener(hireListener);
    String name = listModel.getElementAt(
        list.getSelectedIndex()).toString();

    //創(chuàng)建一個(gè)面板，布局方式采用BoxLayout
    JPanel buttonPane = new JPanel();
    buttonPane.setLayout(new BoxLayout(buttonPane,
                                       BoxLayout.LINE_AXIS));
    buttonPane.add(fireButton);
    buttonPane.add(Box.createHorizontalStrut(5));
    buttonPane.add(new JSeparator(SwingConstants.VERTICAL));
    buttonPane.add(Box.createHorizontalStrut(5));
    buttonPane.add(employeeName);
    buttonPane.add(hireButton);
    buttonPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));

    add(listScrollPane, BorderLayout.CENTER);
    add(buttonPane, BorderLayout.PAGE_END);
  }

  class FireListener
      implements ActionListener {
    public void actionPerformed(ActionEvent e) {
      /*
       *方法用于將所選項(xiàng)刪除
       */
      int index = list.getSelectedIndex();
      listModel.remove(index);

      int size = listModel.getSize();

      if (size == 0) {
        //fireButton按鈕不可用
        fireButton.setEnabled(false);

      }
      else { //選擇一項(xiàng)
        if (index == listModel.getSize()) {
          //除去最后一項(xiàng)
          index--;
        }

        list.setSelectedIndex(index);
        list.ensureIndexIsVisible(index);
      }
    }
  }

  //HireListener類主要封裝文本區(qū)域和"增加"按鈕事件響應(yīng)的方法
  class HireListener
      implements ActionListener, DocumentListener {
    private boolean alreadyEnabled = false;
    private JButton button;

    public HireListener(JButton button) {
      this.button = button;
    }

    //actionPerformed(ActionEvent e)  方法用來(lái)為ActionListener調(diào)用
    public void actionPerformed(ActionEvent e) {
      String name = employeeName.getText();
      if (name.equals("") || alreadyInList(name)) {
        Toolkit.getDefaultToolkit().beep();
        employeeName.requestFocusInWindow();
        employeeName.selectAll();
        return;
      }

      int index = list.getSelectedIndex(); //取得選項(xiàng)的序號(hào)
      if (index == -1) { //如果沒(méi)有一項(xiàng)被選擇，則第一項(xiàng)被選擇
        index = 0;
      }
      else {
        index++;
      }

      listModel.insertElementAt(employeeName.getText(), index);
      employeeName.requestFocusInWindow();
      employeeName.setText("");
      list.setSelectedIndex(index);
      list.ensureIndexIsVisible(index);
    }

    protected boolean alreadyInList(String name) {
      return listModel.contains(name);
    }

    //insertUpdate(DocumentEvent e)  方法用來(lái)為DocumentListener調(diào)用
    public void insertUpdate(DocumentEvent e) {
      enableButton();
    }

    //removeUpdate(DocumentEvent e)  方法用來(lái)為DocumentListener調(diào)用
    public void removeUpdate(DocumentEvent e) {
      handleEmptyTextField(e);
    }

    //changedUpdate(DocumentEvent e)  方法用來(lái)為DocumentListener調(diào)用
    public void changedUpdate(DocumentEvent e) {
      if (!handleEmptyTextField(e)) {
        enableButton();
      }
    }

    private void enableButton() {
      if (!alreadyEnabled) {
        button.setEnabled(true);
      }
    }

    private boolean handleEmptyTextField(DocumentEvent e) {
      if (e.getDocument().getLength() <= 0) {
        button.setEnabled(false);
        alreadyEnabled = false;
        return true;
      }
      return false;
    }
  }

  /**
   * valueChanged(ListSelectionEvent e) 方法用來(lái)為L(zhǎng)istSelectionListener調(diào)用
   */
  public void valueChanged(ListSelectionEvent e) {
    if (e.getValueIsAdjusting() == false) {
      if (list.getSelectedIndex() == -1) {
        //沒(méi)有選項(xiàng)被選種，則"刪除"按鈕不可用
        fireButton.setEnabled(false);
      }
      else {
        //有選項(xiàng)被選種，則"刪除"可用
        fireButton.setEnabled(true);
      }
    }
  }

  /**
   * createAndShowGUI() 方法用來(lái)創(chuàng)建窗體，并顯示
   */
  private static void createAndShowGUI() {
    //使界面有好的視覺(jué)效果
    JFrame.setDefaultLookAndFeelDecorated(true);
    //創(chuàng)建窗體
    JFrame frame = new JFrame("ListTest");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JComponent newContentPane = new ListTest();
    newContentPane.setOpaque(true);
    frame.setContentPane(newContentPane);
    //顯示窗體
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    //顯示窗體
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}