More Swing

1
More Swing

• COMP204, Bernhard Pfahringer

2
Animations javax.swing.Timer

• ActionListener incrementYPosition new
  ActionListener()
• public void actionPerformed(ActionEvent evt)
• if (_y lt 400)
• _y
• if (_frame ! null) _frame.repaint()
• else
• _timer.stop()
• _timer new javax.swing.Timer(10,incrementYPositi
  on)
• _timer.start()

3
Safe loading of an ImageIcon

• / Returns an ImageIcon, or null if the path
  was invalid. /
• protected static ImageIcon createImageIcon(String
  path)
• java.net.URL imgURL ButtonDemo.class.getReso
  urce(path)
• if (imgURL ! null)
• return new ImageIcon(imgURL)
• else
• System.err.println("Couldn't find file "
  path)
• return null

4
ButtonDemo action method

• public void actionPerformed(ActionEvent e)
• if ("disable".equals(e.getActionCommand()))
• b2.setEnabled(false)
• b1.setEnabled(false)
• b3.setEnabled(true)
• else
• b2.setEnabled(true)
• b1.setEnabled(true)
• b3.setEnabled(false)

5
Setting up a button

• b1 new JButton("Disable middle button",
  leftButtonIcon)
• b1.setVerticalTextPosition(AbstractButton.CENTER)
  
• //aka LEFT, for left-to-right locales
  
• b1.setHorizontalTextPosition(AbstractButton.LEADIN
  G)
• b1.setMnemonic(KeyEvent.VK_D)
• b1.setActionCommand("disable")
• b1.addActionListener(this)
• b1.setToolTipText("Click this button to disable
  the middle button.")

6
JCheckbox

• Maintain/display labeled binary state (on/off,
  yes/no, selected/unselected)
• getLabel(), setLabel(String),
• isSelected(), setSelected()
• also an ItemListener for an ItemEvent

7
Trivial example

• import javax.swing.
• import java.awt.
• import java.awt.event.
• public class CheckBoxTest extends JFrame
• private JCheckBox cb new JCheckBox("off")
• public static void main(String args)
• CheckBoxTest w new CheckBoxTest()
• w.show()

8
cont.

• public CheckBoxTest()
• setTitle("CheckBoxTest")
• setSize(300,70)
• cb.addItemListener(new CheckBoxTestListener())
  
• add("Center", cb)
• private class CheckBoxTestListener implements
  ItemListener
• public void itemStateChanged(ItemEvent e)
• cb.setLabel( (cb.isSelected()) ? "ON"
  "OFF")

9
RadioButtonDemo

• public class RadioButtonDemo extends JPanel
• implements
  ActionListener
• static String birdString "Bird"
• .
• JRadioButton birdButton new JRadioButton(birdSt
  ring)
• birdButton.setMnemonic(KeyEvent.VK_B)
• birdButton.setActionCommand(birdString)
• birdButton.setSelected(true)
• ....
• ButtonGroup group new ButtonGroup()
• group.add(birdButton)
• group.add(catButton)

10
cont.

• birdButton.addActionListener(this)
• JPanel radioPanel new JPanel(new GridLayout(0,
  1))
  
• radioPanel.add(birdButton)
• add(radioPanel, BorderLayout.LINE_START)
• add(picture, BorderLayout.CENTER)
• setBorder(BorderFactory.createEmptyBorder(20,20,2
  0,20))
• public void actionPerformed(ActionEvent e)
• picture.setIcon(createImageIcon("images/"
• 
  e.getActionCommand() ".gif"))

11
Dialogs

• Special purpose window displayed shortly
• To notify, or ask simple questions
• Always attached to a Frame
• Modal demands user response, prevents further
  actions show() wont return until dismissed, ?
  setVisible(false)
• Nonmodal actions often placed into separate
  Thread
• Dialog dig new Dialog(this,false)

12
Dialog example

• public class DialogTest extends JFrame
• public static void main(String args)
• DialogTest w new DialogTest()
  w.show()
• private JTextArea d new JTextArea()
• private JCheckBox cb new JCheckBox("Modal
  Dialog?")
• public DialogTest()
• setTitle("DialogTest") setSize(300,220)
• add("West",cb) add("East",new
  MakeButton()) add("South",d)

13
cont

• private void makeDialog(boolean modalFlag)
• final JDialog dialog new JDialog(this,modalF
  lag)
• dialog.setSize(100,100)
• dialog.add("North",new CountButton(1))
• dialog.add("West",new CountButton(2))
• dialog.add("East",new CountButton(3))
• dialog.add("South", new ButtonAdapter("Hide")
  
• public void pressed()
• dialog.setVisible(false)
• )
• dialog.show()

14
cont.

• private class MakeButton extends ButtonAdapter
• public MakeButton() super("Make Dialog")
  
• public void pressed() makeDialog(cb.isSele
  cted())
• private class CountButton extends ButtonAdapter
  
• public CountButton(int value) super(""
  value)
• public void pressed() d.append("Button "
  getLabel() " pressed\n")

15
JFileChooser

• import javax.swing.filechooser.
• fc new JFileChooser()
• public void actionPerformed(ActionEvent e)
  
  if (e.getSource()
  openButton)
• int returnVal fc.showOpenDialog(FileChoo
  serDemo.this)
• if (returnVal JFileChooser.APPROVE_OPTI
  ON)
• File file fc.getSelectedFile()
• // This is where a real application
  would open the file.
  
• log.append("Opening "
  file.getName() "." newline)
• else
• log.append("Open command cancelled by
  user." newline)
• log.setCaretPosition(log.getDocument().getLen
  gth())

16
JMenuBar

• Attached to JFrame by setJMenuBar()
• JMenuBar bar new JMenuBar()
• setJMenuBar(bar)
• Add menus
• JMenu HelpMenu new JMenu(Help)
• bar.add(helpMenu)
• Add menu items
• JMenuItem quitItem new JMenuItem(Quit)
• quitItem.addActionListener(new QuitListener())
• helpMenu.add(quitItem)