Лекция 09. GUI.Swing
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Введение
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Пакеты
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Для построения GUI в Java используются следующие основные пакеты:


#. **Awt** - появился в первых версиях, используется мало.
#. **Swing** - самый популярный пакет.
#. **JavaFX** - современный и перспективный.


Awt пример
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.. image:: _static/09/awt-overview.png


Swing пример
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.. image:: _static/09/swing-overview.png


JavaFX пример
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.. image:: _static/09/fx-sample.png


Сравнение
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Недостатки **awt**:


* ''тяжеловесные'' компоненты (системозависимые);
* невозможность изменения внешнего вида.

Недостатки **swing**:


* ограничения в изменении внешнего вида;
* ориентация на desktop-приложения.

Swing
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Основы
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Простое приложение
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Рассмотрим простейшее **Swing**-приложение.



.. code-block:: java

 import javax.swing.*;
 
 public class Simple 
 {
    public static void main (String [] args) {
       JFrame myWindow = new JFrame("Пробное окно");
       myWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       myWindow.setSize(400, 300);
       myWindow.setVisible(true);
    }
 }



Контейнеры верхнего уровня
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Все **swing**-программы должны включать в себя **Контейнеры первого уровня**


* **JFrame**
* **JApplet**
* **JWindow**
* **JDialog**
Эти контейнеры находятся на вершине иерархии контейнеров и 

содержат в себе другие, ''легковесные'' контейнеры и элементы

управления.
Разница между **JFrame** и **JWindow** может быть показана

на следующем примере:



.. code-block:: java

 import javax.swing.*;
 
 public class Simple 
 {
    public static void main (String [] args) {
       JFrame win1 = new JFrame("JFrame");
       win1.setSize(400, 300);
       win1.setLocation(10,10);
 
       JWindow win2 = new JWindow();
       win2.setSize(200,300);
       win2.setLocation(500,200);
       
       win1.setVisible(true);
       win2.setVisible(true);
    }
 }


Окно **JFrame**, в отличие от **JWindow** 

обладает заголовком, кнопками управления. 

Обработка событий
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События
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Рассмотрим пример с обработкой события:



.. code-block:: java

 import javax.swing.*;
 import java.awt.*;
 import java.awt.event.*;
 
 public class Simple 
 {
    public static void main (String [] args) {
       JFrame myWindow = new JFrame("Пробное окно");
       myWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       myWindow.setSize(400, 300);
    
       myWindow.setLayout(new FlowLayout());
 
       JButton btn1 = new JButton("Привет!");
       JButton btn2 = new JButton("Пока!");




.. code-block:: java

   btn1.addActionListener(new ActionListener() {
     public void actionPerformed(ActionEvent ae) {
      JOptionPane.showMessageDialog(null,"Привет","Нажато",
                                  JOptionPane.WARNING_MESSAGE);
      }
     });
 
     myWindow.add(btn1);
     myWindow.add(btn2);
      
     myWindow.setVisible(true);
    }
 }


Для размещения кнопок в окне приложения мы должны использовать 

**менеджеры компоновки**:


* **BorderLayout**
* **FlowLayout**
* **GridLayout**
* **GridBagLayout**
* **BoxLayout**
* **CardLayout**
* **GroupLayout**
* **SpringLayout**

Обзор компонентов
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Button
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Класс **JButton**



.. code-block:: java

 JButton btn = new JButton("Title");





.. code-block:: java

 JButton(Icon);
 JButton(String);
 JButton(String,Icon);




.. code-block:: java

 protected static ImageIcon createImageIcon(String path) {
     java.net.URL imgURL = ButtonDemo.class.getResource(path);
     return new ImageIcon(imgURL);
 }
 ..
 ImageIcon ic = createImageIcon("images/icon1.gif");
 JButton btn1 = new JButton(ic);
 ..



TextField
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.. code-block:: java

 JTextField(int cols);
 JTextField(String str,int cols);
 JTextField(String str);




.. code-block:: java

 textfield.addActionListener(this);
 ..
 public void actionPerformed(ActionEvent evt) {
   String text=textfield.getText();
   ..
   textfield.setText("Новый текст");
   ..
 }



Password
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.. code-block:: java

 ..
 private static String OK = "ok";
 ..
 passfield = new JPasswordField(10);
 passfield.setActionCommand(OK);
 passfield.setActionListener(this);
 ..
 btn.setActionCommand(OK);
 ..
 public void setActionPerformed(ActionEvent evt) {
    String cmd = ebv.getActionCommand();
    if(OK.equals(cmd)) {
       char[] pass=passfield.getPassword();
       ..
    }
 }



TextArea
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.. code-block:: java

 text = new JTextArea();
 ..
 text.setColumns(20);
 text.setLineWrap(true);
 text.setRows(5);
 text.setEditable(true);
 ..
 text.getText();
 text.setText("...");
 ..



CheckBox
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.. code-block:: java

 check = new JCheckBox("Photo");
 check.setSelected(true);
 ..
 check.addItemListener(new ItemListener() {
    public void itemStateChanged(ItemIvent e) {
       if(check.isSelected())...
    }
 }
 



RadioButton
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.. code-block:: java

 private static String RED="Red";
 private static String BLUE="Blue";
 ..
 rbColorRed = new JRadioButton(RED);
 rbColorBlue = new JRadioButton(BLUE);
 rbColorRed.setActionCommand(RED);
 rbColorBlue.setActionCommand(BLUE);
 rbColorRed.setSelected(true);
 ..
 ButtonGroup group = new ButtonGroup();
 group.add(rbColorRed);
 group.add(rbColorBlue);
 ..
 rbColorRed.addActionListener(this);
 rbColorBlue.addActionListener(this);
 ..
 public void actionPerformed(ActionEvent e) {
     picture.setIcon(new ImageIcon("images/" 
                                   + e.getActionCommand() 
                                   + ".gif"));
 }



Dialogs
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MessageBox
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.. code-block:: java

 import javax.swing.JOptionPane
 
 public class ClassNameHere {
     public static void infoBox(String infoMessage, String titleBar) {
         JOptionPane.showMessageDialog(null, infoMessage, 
                                       "InfoBox: " + titleBar, 
                                       JOptionPane.INFORMATION_MESSAGE);
     }
 }


Варианты:


* JOptionPane.WARNING_MESSAGE
* JOptionPane.ERROR_MESSAGE
* JOptionPane.PLAIN_MESSAGE
* JOptionPane.INFORMATION_MESSAGE

.. image:: _static/09/icons.png



.. code-block:: java

 //Custom button text
 Object[] options = {"Yes, please",
                     "No, thanks",
                     "No eggs, no ham!"};
 int n = JOptionPane.showOptionDialog(frame,
     "Would you like some green eggs to go "
     + "with that ham?",
     "A Silly Question",
     JOptionPane.YES_NO_CANCEL_OPTION,
     JOptionPane.QUESTION_MESSAGE,
     null,
     options,
     options[2])



.. image:: _static/09/eggs.png


Вопросы для самоконтроля
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