Swing part 1

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Swing part 1

• Examples using
• Basic widgets and features

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How to learn new a widget

• How does it looks?
• The Swing tutorial has a visual index
• What does it do?
• What properties does it have?
• What meaningful events does if fire?
• What data does is supplies?
• Data properties, like value or text

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Hierarchy of Swing p1
Component
Container
Window
JComponent
Dialog
Frame
JPanel
JFrame
JDialog
JWindow
JApplet
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Hierarchy of Swing p2
JComponent
JTextComponent
JComboBox
JButton
JCheckBox
JLabel
JTextField
JTextArea
JList
JScrollBar
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The JComponent class

• Root class for Swings widgets (except top-level)
• Based on AWT container
• A simple Swing widget is a composite AWT widget
• But it doesnt mean you should exploit this!
• Supports basic properties and events
• Widgets state
• Basic appearance
• Layout properties
• Mouse and key events

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Widgets state properties

• Visible or not
• Enabled / disabled
• Disabled widgets do not respond and are grayed
  out
• Tool tip text
• Important for helping the user
• Name
• Each widget has a name which identifies it within
  the containing widget

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Basic appearance properties

• Foreground and background color
• Mostly handled by the look feel
• Opaque or transparent
• Font (for text)
• Border
• Borders can surrounds all widgets
• Useful mainly for panels
• To be mentioned in details later

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Basic layout properties

• Usually the laying out will be done by the layout
  manager of the containing widget
• The programmer can supply tips for the layout
• Minimum and maximum size
• Preferred size
• X and Y alignment
• Most widgets (buttons, labels, toolbars...) will
  handle size automatically

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Common events

• All widgets support mouse and key events
• Mouse event occurs in respond to mouse pointer
  actions
• Motions
• Clicks
• But usually the widget will handle those
• Key events respond to key pressing
• Used for key accelerators

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Example One Your First Swing Program

• We will write simple program HelloWorldSwing
• And here's the full code for HelloWorldSwing
• import javax.swing.
• public class HelloWorldSwing
• / Create the GUI and show it. For thread
  safety,this method should be invoked from the
  event-dispatching thread. /

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• private static void createAndShowGUI()
• //Make sure we have nice window decorations.
  JFrame.setDefaultLookAndFeelDecorated(true)
  //Create and set up the window.
• JFrame frame new JFrame("HelloWorldSwing")
• frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS
  E)
• //Add the ubiquitous "Hello World" label.
• JLabel label new JLabel("Hello World")
  frame.getContentPane().add(label)
• //Display the window.
• frame.pack()
• frame.setVisible(true)

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Main function

• public static void main(String args)
• createAndShowGUI()

Basic code of every swing program 1.Import the
pertinent packages. 2.Set up a top-level
container. 3.Display the container.
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Thread envelope

• javax.swing.SwingUtilities.invokeLater(new
  Runnable()
• public void run()
• / create and show the GUI / )

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Example Two SwingApplication

• Topics illustrated in this example
• Look and Feel
• Setting Up Buttons and Labels
• Adding Components to Containers
• Adding Borders Around Components
• Handling Events

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Example Two SwingApplication
Each time the user clicks the button (JButton),
the label (JLabel) is updated.
JButton
JLabel
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Setting Up Buttons and Labels

• JButton button new JButton("I'm a Swing
  button!")
• button.setMnemonic('i')
• button.addActionListener(/...create an action
  listener.../)
• ...// where instance variables are declared
• private static String labelPrefix "Number of
  button clicks "
• private int numClicks 0
• ...// in GUI initialization code
• final JLabel label new JLabel(labelPrefix "0
  ")
• ...// in the event handler for button clicks
• label.setText(labelPrefix numClicks)

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Look and Feel
GTK look and feel
Java look and feel
Mac OS look and feel
Windows look and feel
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Look and Feel code

• String lookAndFeel null
• lookAndFeel UIManager.getCrossPlatformLookAndFe
  elClassName()
• try UIManager.setLookAndFeel(lookAndFeel)
  catch (Exception e)

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Adding Components to Containers

• JPanel panel new JPanel(new GridLayout (0,1))
• panel.add(button)
• panel.add(label)
• panel.setBorder(BorderFactory.createEmptyBord(
• 30, //top
• 30, //left
• 10, //bottom
• 30) //right ))

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Handling Events

• public class SwingApplication implements
  ActionListener
• JButton button new JButton("I'm a Swing
  button!")
• button.addActionListener(this)
• public void actionPerformed(ActionEvent e)
  numClicks
• label.setText(labelPrefix numClicks)

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Example Three CelsiusConverter

• JTextField tempCelsius null
• tempCelsius new JTextField(5)
• convertTemp.addActionListener(this)
• tempCelsius.addActionListener(this)
• public void actionPerformed(ActionEvent event)
  //Parse degrees Celsius as a double and convert
  to Fahrenheit.
• int tempFahr
• (int)((Double.parseDouble(tempCelsius.getText()))
  1.8 32)
• fahrenheitLabel.setText(tempFahr "
  Fahrenheit")