More Interfaces and JList

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More Interfacesand JList

• Rick Mercer

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Displaying an Image

• Use JOptionPane to display message
• JOptionPane.showMessageDialog(null,
• "Hello, World!")
• Note icon to the left (i for information

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ImageIcon implements Icon

• JOptionPane.showMessageDialog(null, "Hello,
  World!", "Message",
• JOptionPane.INFORMATION_MESSAGE, new
  ImageIcon("home34.jpg"))

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Here is the method heading

• public static void showMessageDialog(Component par
  entComponent,
• Object message,
• String title,
• int messageType,
• Icon icon)
• The 5th parameter is Icon, an interface
• The argument must be an instance of a class that
  implements the Icon interface
• Such as ImageIcon

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Demo javax.swing.Timer

• // Use a javax.swing.Timer to show seconds tick
  by
• import java.awt.event.ActionEvent
• import java.awt.event.ActionListener
• import javax.swing.JFrame
• import javax.swing.JLabel
• import javax.swing.Timer
• public class TimerDemo extends JFrame
• public static void main(String args)
• JFrame window new TimerDemo()
• window.setVisible(true)
• private Timer timer
• private int currentSecond
• private JLabel secondsGoneBy
• new JLabel("", JLabel.CENTER)

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A listener to show seconds tick

• public TimerDemo()
• setSize(50, 80)
• setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
• getContentPane().add(secondsGoneBy)
• // Construct a timer with the delay and
  listener

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Other Events and Components?

• Yes indeed
• There are many more graphical components
• There are many more types of events
• There are other layout managers
• We can draw and do animations?
• But what else do we need for Jukebox?
• A JList to show Songs that can be selected with a
  button click

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JList Objects

• JList provides a view of objects in a graphical
  manner Users can select single or multiple
  selections
• Can determine the selected cell or set any cell
  to be "selected"
• // Returns the first selected index returns
  -1
• // if there is no selected item.
• public int getSelectedIndex()
• // Selects a single cell in this JList //
  and highlights the element in that cell
• public void setSelectedIndex(int index)

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Adapt with ListModel

• JLists store a list that must implement the
  ListModel interface
• You need to adapt your collection to have the
  methods JList needs to show and select elements
• Constructor and setModel of JList require an
  object from a class that implements ListModel
• // Construct a view with any class that //
  implements ListModel
• public JList(ListModel dataModel)
• // Or later set the model to a ListModel
• public void setModel(ListModel dataMmodel)

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First a test

• import static org.junit.Assert.
• import org.junit.Test
• public class AccountCollectionTest
• _at_Test
• public void testGetElementAtAndGetSize()
• // Plan to start with four section leaders
• AccountCollection allAccounts new
  AccountCollection()
• assertEquals(4, allAccounts.getSize())
• // I would like to possible add others after
  initialization
• allAccounts.addBankAccount(new
  BankAccount("Another", 20.00))
• allAccounts.addBankAccount(new
  BankAccount("Last one", 30.00))
• assertEquals(6, allAccounts.getSize())
• // These are NOT in order like your
  SongCollection must be
• BankAccount currentAccount
  allAccounts.getElementAt(0)
• assertEquals("Jessica", allAccounts.getElementA
  t(0).getID())
• assertEquals("Andreea", allAccounts.getElementA
  t(1).getID())

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Have your collection implement ListModel

• import java.util.ArrayList
• import javax.swing.ListModel
• import javax.swing.event.ListDataListener
• public class AccountCollection implements
  ListModel
• private ArrayListltBankAccountgt list
• // Wierd initialization. Always begin with
  these four
• public AccountCollection()
• list new ArrayListltBankAccountgt()
• list.add(new BankAccount("Jessica", 100))
• list.add(new BankAccount("Andreea", 100))
• list.add(new BankAccount("Mark", 100))
• list.add(new BankAccount("Mike", 100))
• public void addBankAccount(BankAccount a)
• list.add(a)

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Implement Two methods only

• public int getSize()
• return list.size()
• public BankAccount getElementAt(int index)
• return list.get(index)
• public void addListDataListener(ListDataListener
  l)
• // TODO Auto-generated method stub
• public void removeListDataListener(ListDataListe
  ner l)
• // TODO Auto-generated method stub

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Show collection in a GUI

• import java.awt.
• import javax.swing.
• public class ShowListInAGui extends JFrame
• public static void main(String args)
• ShowListInAGui aWindow new
  ShowListInAGui()
• aWindow.setVisible(true)
• // The model for this application
• private AccountCollection model
• // Show all ListModel elements in a Graphical
  manner
• private JList view
• // A Button that will have a listener
  registered to it
• private JButton theButton new JButton("Click
  me")

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No Events Yet

• public ShowListInAGui()
• // Initialize the model
• model new AccountCollection()
• model.addBankAccount(new BankAccount("Rick",
  0.00))
• model.addBankAccount(new BankAccount("Chris",
  567.89))
• view new JList(model)
• // Set up the GUI
• setLocation(100, 100)
• setSize(100, 300)
• setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)
  
• Container contentPane getContentPane()
• contentPane.add(view, BorderLayout.CENTER)
• contentPane.add(theButton, BorderLayout.SOUTH)
  

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In teams of 2 or 3

• Complete code in handout